drm: reference count event->completion

[linux-2.6-microblaze.git] / drivers / gpu / drm / drm_atomic_helper.c

/*
 * Copyright (C) 2014 Red Hat
 * Copyright (C) 2014 Intel Corp.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 * Rob Clark <robdclark@gmail.com>
 * Daniel Vetter <daniel.vetter@ffwll.ch>
 */

#include <drm/drmP.h>
#include <drm/drm_atomic.h>
#include <drm/drm_plane_helper.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_atomic_helper.h>
#include <linux/dma-fence.h>

#include "drm_crtc_internal.h"

/**
 * DOC: overview
 *
 * This helper library provides implementations of check and commit functions on
 * top of the CRTC modeset helper callbacks and the plane helper callbacks. It
 * also provides convenience implementations for the atomic state handling
 * callbacks for drivers which don't need to subclass the drm core structures to
 * add their own additional internal state.
 *
 * This library also provides default implementations for the check callback in
 * drm_atomic_helper_check() and for the commit callback with
 * drm_atomic_helper_commit(). But the individual stages and callbacks are
 * exposed to allow drivers to mix and match and e.g. use the plane helpers only
 * together with a driver private modeset implementation.
 *
 * This library also provides implementations for all the legacy driver
 * interfaces on top of the atomic interface. See drm_atomic_helper_set_config(),
 * drm_atomic_helper_disable_plane(), drm_atomic_helper_disable_plane() and the
 * various functions to implement set_property callbacks. New drivers must not
 * implement these functions themselves but must use the provided helpers.
 *
 * The atomic helper uses the same function table structures as all other
 * modesetting helpers. See the documentation for &struct drm_crtc_helper_funcs,
 * struct &drm_encoder_helper_funcs and &struct drm_connector_helper_funcs. It
 * also shares the &struct drm_plane_helper_funcs function table with the plane
 * helpers.
 */
static void
drm_atomic_helper_plane_changed(struct drm_atomic_state *state,
                                struct drm_plane_state *plane_state,
                                struct drm_plane *plane)
{
        struct drm_crtc_state *crtc_state;

        if (plane->state->crtc) {
                crtc_state = drm_atomic_get_existing_crtc_state(state,
                                                                plane->state->crtc);

                if (WARN_ON(!crtc_state))
                        return;

                crtc_state->planes_changed = true;
        }

        if (plane_state->crtc) {
                crtc_state = drm_atomic_get_existing_crtc_state(state,
                                                                plane_state->crtc);

                if (WARN_ON(!crtc_state))
                        return;

                crtc_state->planes_changed = true;
        }
}

static int handle_conflicting_encoders(struct drm_atomic_state *state,
                                       bool disable_conflicting_encoders)
{
        struct drm_connector_state *conn_state;
        struct drm_connector *connector;
        struct drm_connector_list_iter conn_iter;
        struct drm_encoder *encoder;
        unsigned encoder_mask = 0;
        int i, ret = 0;

        /*
         * First loop, find all newly assigned encoders from the connectors
         * part of the state. If the same encoder is assigned to multiple
         * connectors bail out.
         */
        for_each_connector_in_state(state, connector, conn_state, i) {
                const struct drm_connector_helper_funcs *funcs = connector->helper_private;
                struct drm_encoder *new_encoder;

                if (!conn_state->crtc)
                        continue;

                if (funcs->atomic_best_encoder)
                        new_encoder = funcs->atomic_best_encoder(connector, conn_state);
                else if (funcs->best_encoder)
                        new_encoder = funcs->best_encoder(connector);
                else
                        new_encoder = drm_atomic_helper_best_encoder(connector);

                if (new_encoder) {
                        if (encoder_mask & (1 << drm_encoder_index(new_encoder))) {
                                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] on [CONNECTOR:%d:%s] already assigned\n",
                                        new_encoder->base.id, new_encoder->name,
                                        connector->base.id, connector->name);

                                return -EINVAL;
                        }

                        encoder_mask |= 1 << drm_encoder_index(new_encoder);
                }
        }

        if (!encoder_mask)
                return 0;

        /*
         * Second loop, iterate over all connectors not part of the state.
         *
         * If a conflicting encoder is found and disable_conflicting_encoders
         * is not set, an error is returned. Userspace can provide a solution
         * through the atomic ioctl.
         *
         * If the flag is set conflicting connectors are removed from the crtc
         * and the crtc is disabled if no encoder is left. This preserves
         * compatibility with the legacy set_config behavior.
         */
        drm_connector_list_iter_get(state->dev, &conn_iter);
        drm_for_each_connector_iter(connector, &conn_iter) {
                struct drm_crtc_state *crtc_state;

                if (drm_atomic_get_existing_connector_state(state, connector))
                        continue;

                encoder = connector->state->best_encoder;
                if (!encoder || !(encoder_mask & (1 << drm_encoder_index(encoder))))
                        continue;

                if (!disable_conflicting_encoders) {
                        DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] in use on [CRTC:%d:%s] by [CONNECTOR:%d:%s]\n",
                                         encoder->base.id, encoder->name,
                                         connector->state->crtc->base.id,
                                         connector->state->crtc->name,
                                         connector->base.id, connector->name);
                        ret = -EINVAL;
                        goto out;
                }

                conn_state = drm_atomic_get_connector_state(state, connector);
                if (IS_ERR(conn_state)) {
                        ret = PTR_ERR(conn_state);
                        goto out;
                }

                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] in use on [CRTC:%d:%s], disabling [CONNECTOR:%d:%s]\n",
                                 encoder->base.id, encoder->name,
                                 conn_state->crtc->base.id, conn_state->crtc->name,
                                 connector->base.id, connector->name);

                crtc_state = drm_atomic_get_existing_crtc_state(state, conn_state->crtc);

                ret = drm_atomic_set_crtc_for_connector(conn_state, NULL);
                if (ret)
                        goto out;

                if (!crtc_state->connector_mask) {
                        ret = drm_atomic_set_mode_prop_for_crtc(crtc_state,
                                                                NULL);
                        if (ret < 0)
                                goto out;

                        crtc_state->active = false;
                }
        }
out:
        drm_connector_list_iter_put(&conn_iter);

        return ret;
}

static void
set_best_encoder(struct drm_atomic_state *state,
                 struct drm_connector_state *conn_state,
                 struct drm_encoder *encoder)
{
        struct drm_crtc_state *crtc_state;
        struct drm_crtc *crtc;

        if (conn_state->best_encoder) {
                /* Unset the encoder_mask in the old crtc state. */
                crtc = conn_state->connector->state->crtc;

                /* A NULL crtc is an error here because we should have
                 *  duplicated a NULL best_encoder when crtc was NULL.
                 * As an exception restoring duplicated atomic state
                 * during resume is allowed, so don't warn when
                 * best_encoder is equal to encoder we intend to set.
                 */
                WARN_ON(!crtc && encoder != conn_state->best_encoder);
                if (crtc) {
                        crtc_state = drm_atomic_get_existing_crtc_state(state, crtc);

                        crtc_state->encoder_mask &=
                                ~(1 << drm_encoder_index(conn_state->best_encoder));
                }
        }

        if (encoder) {
                crtc = conn_state->crtc;
                WARN_ON(!crtc);
                if (crtc) {
                        crtc_state = drm_atomic_get_existing_crtc_state(state, crtc);

                        crtc_state->encoder_mask |=
                                1 << drm_encoder_index(encoder);
                }
        }

        conn_state->best_encoder = encoder;
}

static void
steal_encoder(struct drm_atomic_state *state,
              struct drm_encoder *encoder)
{
        struct drm_crtc_state *crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *connector_state;
        int i;

        for_each_connector_in_state(state, connector, connector_state, i) {
                struct drm_crtc *encoder_crtc;

                if (connector_state->best_encoder != encoder)
                        continue;

                encoder_crtc = connector->state->crtc;

                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] in use on [CRTC:%d:%s], stealing it\n",
                                 encoder->base.id, encoder->name,
                                 encoder_crtc->base.id, encoder_crtc->name);

                set_best_encoder(state, connector_state, NULL);

                crtc_state = drm_atomic_get_existing_crtc_state(state, encoder_crtc);
                crtc_state->connectors_changed = true;

                return;
        }
}

static int
update_connector_routing(struct drm_atomic_state *state,
                         struct drm_connector *connector,
                         struct drm_connector_state *connector_state)
{
        const struct drm_connector_helper_funcs *funcs;
        struct drm_encoder *new_encoder;
        struct drm_crtc_state *crtc_state;

        DRM_DEBUG_ATOMIC("Updating routing for [CONNECTOR:%d:%s]\n",
                         connector->base.id,
                         connector->name);

        if (connector->state->crtc != connector_state->crtc) {
                if (connector->state->crtc) {
                        crtc_state = drm_atomic_get_existing_crtc_state(state, connector->state->crtc);
                        crtc_state->connectors_changed = true;
                }

                if (connector_state->crtc) {
                        crtc_state = drm_atomic_get_existing_crtc_state(state, connector_state->crtc);
                        crtc_state->connectors_changed = true;
                }
        }

        if (!connector_state->crtc) {
                DRM_DEBUG_ATOMIC("Disabling [CONNECTOR:%d:%s]\n",
                                connector->base.id,
                                connector->name);

                set_best_encoder(state, connector_state, NULL);

                return 0;
        }

        funcs = connector->helper_private;

        if (funcs->atomic_best_encoder)
                new_encoder = funcs->atomic_best_encoder(connector,
                                                         connector_state);
        else if (funcs->best_encoder)
                new_encoder = funcs->best_encoder(connector);
        else
                new_encoder = drm_atomic_helper_best_encoder(connector);

        if (!new_encoder) {
                DRM_DEBUG_ATOMIC("No suitable encoder found for [CONNECTOR:%d:%s]\n",
                                 connector->base.id,
                                 connector->name);
                return -EINVAL;
        }

        if (!drm_encoder_crtc_ok(new_encoder, connector_state->crtc)) {
                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] incompatible with [CRTC:%d]\n",
                                 new_encoder->base.id,
                                 new_encoder->name,
                                 connector_state->crtc->base.id);
                return -EINVAL;
        }

        if (new_encoder == connector_state->best_encoder) {
                set_best_encoder(state, connector_state, new_encoder);

                DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] keeps [ENCODER:%d:%s], now on [CRTC:%d:%s]\n",
                                 connector->base.id,
                                 connector->name,
                                 new_encoder->base.id,
                                 new_encoder->name,
                                 connector_state->crtc->base.id,
                                 connector_state->crtc->name);

                return 0;
        }

        steal_encoder(state, new_encoder);

        set_best_encoder(state, connector_state, new_encoder);

        crtc_state = drm_atomic_get_existing_crtc_state(state, connector_state->crtc);
        crtc_state->connectors_changed = true;

        DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d:%s]\n",
                         connector->base.id,
                         connector->name,
                         new_encoder->base.id,
                         new_encoder->name,
                         connector_state->crtc->base.id,
                         connector_state->crtc->name);

        return 0;
}

static int
mode_fixup(struct drm_atomic_state *state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *conn_state;
        int i;
        bool ret;

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                if (!crtc_state->mode_changed &&
                    !crtc_state->connectors_changed)
                        continue;

                drm_mode_copy(&crtc_state->adjusted_mode, &crtc_state->mode);
        }

        for_each_connector_in_state(state, connector, conn_state, i) {
                const struct drm_encoder_helper_funcs *funcs;
                struct drm_encoder *encoder;

                WARN_ON(!!conn_state->best_encoder != !!conn_state->crtc);

                if (!conn_state->crtc || !conn_state->best_encoder)
                        continue;

                crtc_state = drm_atomic_get_existing_crtc_state(state,
                                                                conn_state->crtc);

                /*
                 * Each encoder has at most one connector (since we always steal
                 * it away), so we won't call ->mode_fixup twice.
                 */
                encoder = conn_state->best_encoder;
                funcs = encoder->helper_private;

                ret = drm_bridge_mode_fixup(encoder->bridge, &crtc_state->mode,
                                &crtc_state->adjusted_mode);
                if (!ret) {
                        DRM_DEBUG_ATOMIC("Bridge fixup failed\n");
                        return -EINVAL;
                }

                if (funcs && funcs->atomic_check) {
                        ret = funcs->atomic_check(encoder, crtc_state,
                                                  conn_state);
                        if (ret) {
                                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] check failed\n",
                                                 encoder->base.id, encoder->name);
                                return ret;
                        }
                } else if (funcs && funcs->mode_fixup) {
                        ret = funcs->mode_fixup(encoder, &crtc_state->mode,
                                                &crtc_state->adjusted_mode);
                        if (!ret) {
                                DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] fixup failed\n",
                                                 encoder->base.id, encoder->name);
                                return -EINVAL;
                        }
                }
        }

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                if (!crtc_state->enable)
                        continue;

                if (!crtc_state->mode_changed &&
                    !crtc_state->connectors_changed)
                        continue;

                funcs = crtc->helper_private;
                if (!funcs->mode_fixup)
                        continue;

                ret = funcs->mode_fixup(crtc, &crtc_state->mode,
                                        &crtc_state->adjusted_mode);
                if (!ret) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d:%s] fixup failed\n",
                                         crtc->base.id, crtc->name);
                        return -EINVAL;
                }
        }

        return 0;
}

/**
 * drm_atomic_helper_check_modeset - validate state object for modeset changes
 * @dev: DRM device
 * @state: the driver state object
 *
 * Check the state object to see if the requested state is physically possible.
 * This does all the crtc and connector related computations for an atomic
 * update and adds any additional connectors needed for full modesets and calls
 * down into ->mode_fixup functions of the driver backend.
 *
 * crtc_state->mode_changed is set when the input mode is changed.
 * crtc_state->connectors_changed is set when a connector is added or
 * removed from the crtc.
 * crtc_state->active_changed is set when crtc_state->active changes,
 * which is used for dpms.
 * See also: drm_atomic_crtc_needs_modeset()
 *
 * IMPORTANT:
 *
 * Drivers which set ->mode_changed (e.g. in their ->atomic_check hooks if a
 * plane update can't be done without a full modeset) _must_ call this function
 * afterwards after that change. It is permitted to call this function multiple
 * times for the same update, e.g. when the ->atomic_check functions depend upon
 * the adjusted dotclock for fifo space allocation and watermark computation.
 *
 * RETURNS:
 * Zero for success or -errno
 */
int
drm_atomic_helper_check_modeset(struct drm_device *dev,
                                struct drm_atomic_state *state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *connector_state;
        int i, ret;

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                if (!drm_mode_equal(&crtc->state->mode, &crtc_state->mode)) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d:%s] mode changed\n",
                                         crtc->base.id, crtc->name);
                        crtc_state->mode_changed = true;
                }

                if (crtc->state->enable != crtc_state->enable) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d:%s] enable changed\n",
                                         crtc->base.id, crtc->name);

                        /*
                         * For clarity this assignment is done here, but
                         * enable == 0 is only true when there are no
                         * connectors and a NULL mode.
                         *
                         * The other way around is true as well. enable != 0
                         * iff connectors are attached and a mode is set.
                         */
                        crtc_state->mode_changed = true;
                        crtc_state->connectors_changed = true;
                }
        }

        ret = handle_conflicting_encoders(state, state->legacy_set_config);
        if (ret)
                return ret;

        for_each_connector_in_state(state, connector, connector_state, i) {
                /*
                 * This only sets crtc->connectors_changed for routing changes,
                 * drivers must set crtc->connectors_changed themselves when
                 * connector properties need to be updated.
                 */
                ret = update_connector_routing(state, connector,
                                               connector_state);
                if (ret)
                        return ret;
        }

        /*
         * After all the routing has been prepared we need to add in any
         * connector which is itself unchanged, but who's crtc changes it's
         * configuration. This must be done before calling mode_fixup in case a
         * crtc only changed its mode but has the same set of connectors.
         */
        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                bool has_connectors =
                        !!crtc_state->connector_mask;

                /*
                 * We must set ->active_changed after walking connectors for
                 * otherwise an update that only changes active would result in
                 * a full modeset because update_connector_routing force that.
                 */
                if (crtc->state->active != crtc_state->active) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d:%s] active changed\n",
                                         crtc->base.id, crtc->name);
                        crtc_state->active_changed = true;
                }

                if (!drm_atomic_crtc_needs_modeset(crtc_state))
                        continue;

                DRM_DEBUG_ATOMIC("[CRTC:%d:%s] needs all connectors, enable: %c, active: %c\n",
                                 crtc->base.id, crtc->name,
                                 crtc_state->enable ? 'y' : 'n',
                                 crtc_state->active ? 'y' : 'n');

                ret = drm_atomic_add_affected_connectors(state, crtc);
                if (ret != 0)
                        return ret;

                ret = drm_atomic_add_affected_planes(state, crtc);
                if (ret != 0)
                        return ret;

                if (crtc_state->enable != has_connectors) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d:%s] enabled/connectors mismatch\n",
                                         crtc->base.id, crtc->name);

                        return -EINVAL;
                }
        }

        return mode_fixup(state);
}
EXPORT_SYMBOL(drm_atomic_helper_check_modeset);

/**
 * drm_atomic_helper_check_planes - validate state object for planes changes
 * @dev: DRM device
 * @state: the driver state object
 *
 * Check the state object to see if the requested state is physically possible.
 * This does all the plane update related checks using by calling into the
 * ->atomic_check hooks provided by the driver.
 *
 * It also sets crtc_state->planes_changed to indicate that a crtc has
 * updated planes.
 *
 * RETURNS:
 * Zero for success or -errno
 */
int
drm_atomic_helper_check_planes(struct drm_device *dev,
                               struct drm_atomic_state *state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int i, ret = 0;

        for_each_plane_in_state(state, plane, plane_state, i) {
                const struct drm_plane_helper_funcs *funcs;

                funcs = plane->helper_private;

                drm_atomic_helper_plane_changed(state, plane_state, plane);

                if (!funcs || !funcs->atomic_check)
                        continue;

                ret = funcs->atomic_check(plane, plane_state);
                if (ret) {
                        DRM_DEBUG_ATOMIC("[PLANE:%d:%s] atomic driver check failed\n",
                                         plane->base.id, plane->name);
                        return ret;
                }
        }

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                funcs = crtc->helper_private;

                if (!funcs || !funcs->atomic_check)
                        continue;

                ret = funcs->atomic_check(crtc, crtc_state);
                if (ret) {
                        DRM_DEBUG_ATOMIC("[CRTC:%d:%s] atomic driver check failed\n",
                                         crtc->base.id, crtc->name);
                        return ret;
                }
        }

        return ret;
}
EXPORT_SYMBOL(drm_atomic_helper_check_planes);

/**
 * drm_atomic_helper_check - validate state object
 * @dev: DRM device
 * @state: the driver state object
 *
 * Check the state object to see if the requested state is physically possible.
 * Only crtcs and planes have check callbacks, so for any additional (global)
 * checking that a driver needs it can simply wrap that around this function.
 * Drivers without such needs can directly use this as their ->atomic_check()
 * callback.
 *
 * This just wraps the two parts of the state checking for planes and modeset
 * state in the default order: First it calls drm_atomic_helper_check_modeset()
 * and then drm_atomic_helper_check_planes(). The assumption is that the
 * ->atomic_check functions depend upon an updated adjusted_mode.clock to
 * e.g. properly compute watermarks.
 *
 * RETURNS:
 * Zero for success or -errno
 */
int drm_atomic_helper_check(struct drm_device *dev,
                            struct drm_atomic_state *state)
{
        int ret;

        ret = drm_atomic_helper_check_modeset(dev, state);
        if (ret)
                return ret;

        ret = drm_atomic_helper_check_planes(dev, state);
        if (ret)
                return ret;

        return ret;
}
EXPORT_SYMBOL(drm_atomic_helper_check);

static void
disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
{
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        int i;

        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                const struct drm_encoder_helper_funcs *funcs;
                struct drm_encoder *encoder;

                /* Shut down everything that's in the changeset and currently
                 * still on. So need to check the old, saved state. */
                if (!old_conn_state->crtc)
                        continue;

                old_crtc_state = drm_atomic_get_existing_crtc_state(old_state,
                                                                    old_conn_state->crtc);

                if (!old_crtc_state->active ||
                    !drm_atomic_crtc_needs_modeset(old_conn_state->crtc->state))
                        continue;

                encoder = old_conn_state->best_encoder;

                /* We shouldn't get this far if we didn't previously have
                 * an encoder.. but WARN_ON() rather than explode.
                 */
                if (WARN_ON(!encoder))
                        continue;

                funcs = encoder->helper_private;

                DRM_DEBUG_ATOMIC("disabling [ENCODER:%d:%s]\n",
                                 encoder->base.id, encoder->name);

                /*
                 * Each encoder has at most one connector (since we always steal
                 * it away), so we won't call disable hooks twice.
                 */
                drm_bridge_disable(encoder->bridge);

                /* Right function depends upon target state. */
                if (funcs) {
                        if (connector->state->crtc && funcs->prepare)
                                funcs->prepare(encoder);
                        else if (funcs->disable)
                                funcs->disable(encoder);
                        else if (funcs->dpms)
                                funcs->dpms(encoder, DRM_MODE_DPMS_OFF);
                }

                drm_bridge_post_disable(encoder->bridge);
        }

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                /* Shut down everything that needs a full modeset. */
                if (!drm_atomic_crtc_needs_modeset(crtc->state))
                        continue;

                if (!old_crtc_state->active)
                        continue;

                funcs = crtc->helper_private;

                DRM_DEBUG_ATOMIC("disabling [CRTC:%d:%s]\n",
                                 crtc->base.id, crtc->name);


                /* Right function depends upon target state. */
                if (crtc->state->enable && funcs->prepare)
                        funcs->prepare(crtc);
                else if (funcs->atomic_disable)
                        funcs->atomic_disable(crtc, old_crtc_state);
                else if (funcs->disable)
                        funcs->disable(crtc);
                else
                        funcs->dpms(crtc, DRM_MODE_DPMS_OFF);
        }
}

/**
 * drm_atomic_helper_update_legacy_modeset_state - update legacy modeset state
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * This function updates all the various legacy modeset state pointers in
 * connectors, encoders and crtcs. It also updates the timestamping constants
 * used for precise vblank timestamps by calling
 * drm_calc_timestamping_constants().
 *
 * Drivers can use this for building their own atomic commit if they don't have
 * a pure helper-based modeset implementation.
 */
void
drm_atomic_helper_update_legacy_modeset_state(struct drm_device *dev,
                                              struct drm_atomic_state *old_state)
{
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        int i;

        /* clear out existing links and update dpms */
        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                if (connector->encoder) {
                        WARN_ON(!connector->encoder->crtc);

                        connector->encoder->crtc = NULL;
                        connector->encoder = NULL;
                }

                crtc = connector->state->crtc;
                if ((!crtc && old_conn_state->crtc) ||
                    (crtc && drm_atomic_crtc_needs_modeset(crtc->state))) {
                        struct drm_property *dpms_prop =
                                dev->mode_config.dpms_property;
                        int mode = DRM_MODE_DPMS_OFF;

                        if (crtc && crtc->state->active)
                                mode = DRM_MODE_DPMS_ON;

                        connector->dpms = mode;
                        drm_object_property_set_value(&connector->base,
                                                      dpms_prop, mode);
                }
        }

        /* set new links */
        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                if (!connector->state->crtc)
                        continue;

                if (WARN_ON(!connector->state->best_encoder))
                        continue;

                connector->encoder = connector->state->best_encoder;
                connector->encoder->crtc = connector->state->crtc;
        }

        /* set legacy state in the crtc structure */
        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                struct drm_plane *primary = crtc->primary;

                crtc->mode = crtc->state->mode;
                crtc->enabled = crtc->state->enable;

                if (drm_atomic_get_existing_plane_state(old_state, primary) &&
                    primary->state->crtc == crtc) {
                        crtc->x = primary->state->src_x >> 16;
                        crtc->y = primary->state->src_y >> 16;
                }

                if (crtc->state->enable)
                        drm_calc_timestamping_constants(crtc,
                                                        &crtc->state->adjusted_mode);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_update_legacy_modeset_state);

static void
crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
        int i;

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                if (!crtc->state->mode_changed)
                        continue;

                funcs = crtc->helper_private;

                if (crtc->state->enable && funcs->mode_set_nofb) {
                        DRM_DEBUG_ATOMIC("modeset on [CRTC:%d:%s]\n",
                                         crtc->base.id, crtc->name);

                        funcs->mode_set_nofb(crtc);
                }
        }

        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                const struct drm_encoder_helper_funcs *funcs;
                struct drm_crtc_state *new_crtc_state;
                struct drm_encoder *encoder;
                struct drm_display_mode *mode, *adjusted_mode;

                if (!connector->state->best_encoder)
                        continue;

                encoder = connector->state->best_encoder;
                funcs = encoder->helper_private;
                new_crtc_state = connector->state->crtc->state;
                mode = &new_crtc_state->mode;
                adjusted_mode = &new_crtc_state->adjusted_mode;

                if (!new_crtc_state->mode_changed)
                        continue;

                DRM_DEBUG_ATOMIC("modeset on [ENCODER:%d:%s]\n",
                                 encoder->base.id, encoder->name);

                /*
                 * Each encoder has at most one connector (since we always steal
                 * it away), so we won't call mode_set hooks twice.
                 */
                if (funcs && funcs->atomic_mode_set) {
                        funcs->atomic_mode_set(encoder, new_crtc_state,
                                               connector->state);
                } else if (funcs && funcs->mode_set) {
                        funcs->mode_set(encoder, mode, adjusted_mode);
                }

                drm_bridge_mode_set(encoder->bridge, mode, adjusted_mode);
        }
}

/**
 * drm_atomic_helper_commit_modeset_disables - modeset commit to disable outputs
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * This function shuts down all the outputs that need to be shut down and
 * prepares them (if required) with the new mode.
 *
 * For compatibility with legacy crtc helpers this should be called before
 * drm_atomic_helper_commit_planes(), which is what the default commit function
 * does. But drivers with different needs can group the modeset commits together
 * and do the plane commits at the end. This is useful for drivers doing runtime
 * PM since planes updates then only happen when the CRTC is actually enabled.
 */
void drm_atomic_helper_commit_modeset_disables(struct drm_device *dev,
                                               struct drm_atomic_state *old_state)
{
        disable_outputs(dev, old_state);

        drm_atomic_helper_update_legacy_modeset_state(dev, old_state);

        crtc_set_mode(dev, old_state);
}
EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_disables);

/**
 * drm_atomic_helper_commit_modeset_enables - modeset commit to enable outputs
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * This function enables all the outputs with the new configuration which had to
 * be turned off for the update.
 *
 * For compatibility with legacy crtc helpers this should be called after
 * drm_atomic_helper_commit_planes(), which is what the default commit function
 * does. But drivers with different needs can group the modeset commits together
 * and do the plane commits at the end. This is useful for drivers doing runtime
 * PM since planes updates then only happen when the CRTC is actually enabled.
 */
void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
                                              struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *old_conn_state;
        int i;

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                /* Need to filter out CRTCs where only planes change. */
                if (!drm_atomic_crtc_needs_modeset(crtc->state))
                        continue;

                if (!crtc->state->active)
                        continue;

                funcs = crtc->helper_private;

                if (crtc->state->enable) {
                        DRM_DEBUG_ATOMIC("enabling [CRTC:%d:%s]\n",
                                         crtc->base.id, crtc->name);

                        if (funcs->enable)
                                funcs->enable(crtc);
                        else
                                funcs->commit(crtc);
                }
        }

        for_each_connector_in_state(old_state, connector, old_conn_state, i) {
                const struct drm_encoder_helper_funcs *funcs;
                struct drm_encoder *encoder;

                if (!connector->state->best_encoder)
                        continue;

                if (!connector->state->crtc->state->active ||
                    !drm_atomic_crtc_needs_modeset(connector->state->crtc->state))
                        continue;

                encoder = connector->state->best_encoder;
                funcs = encoder->helper_private;

                DRM_DEBUG_ATOMIC("enabling [ENCODER:%d:%s]\n",
                                 encoder->base.id, encoder->name);

                /*
                 * Each encoder has at most one connector (since we always steal
                 * it away), so we won't call enable hooks twice.
                 */
                drm_bridge_pre_enable(encoder->bridge);

                if (funcs) {
                        if (funcs->enable)
                                funcs->enable(encoder);
                        else if (funcs->commit)
                                funcs->commit(encoder);
                }

                drm_bridge_enable(encoder->bridge);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_enables);

/**
 * drm_atomic_helper_wait_for_fences - wait for fences stashed in plane state
 * @dev: DRM device
 * @state: atomic state object with old state structures
 * @pre_swap: If true, do an interruptible wait, and @state is the new state.
 *      Otherwise @state is the old state.
 *
 * For implicit sync, driver should fish the exclusive fence out from the
 * incoming fb's and stash it in the drm_plane_state.  This is called after
 * drm_atomic_helper_swap_state() so it uses the current plane state (and
 * just uses the atomic state to find the changed planes)
 *
 * Note that @pre_swap is needed since the point where we block for fences moves
 * around depending upon whether an atomic commit is blocking or
 * non-blocking. For async commit all waiting needs to happen after
 * drm_atomic_helper_swap_state() is called, but for synchronous commits we want
 * to wait **before** we do anything that can't be easily rolled back. That is
 * before we call drm_atomic_helper_swap_state().
 *
 * Returns zero if success or < 0 if dma_fence_wait() fails.
 */
int drm_atomic_helper_wait_for_fences(struct drm_device *dev,
                                      struct drm_atomic_state *state,
                                      bool pre_swap)
{
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int i, ret;

        for_each_plane_in_state(state, plane, plane_state, i) {
                if (!pre_swap)
                        plane_state = plane->state;

                if (!plane_state->fence)
                        continue;

                WARN_ON(!plane_state->fb);

                /*
                 * If waiting for fences pre-swap (ie: nonblock), userspace can
                 * still interrupt the operation. Instead of blocking until the
                 * timer expires, make the wait interruptible.
                 */
                ret = dma_fence_wait(plane_state->fence, pre_swap);
                if (ret)
                        return ret;

                dma_fence_put(plane_state->fence);
                plane_state->fence = NULL;
        }

        return 0;
}
EXPORT_SYMBOL(drm_atomic_helper_wait_for_fences);

/**
 * drm_atomic_helper_wait_for_vblanks - wait for vblank on crtcs
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * Helper to, after atomic commit, wait for vblanks on all effected
 * crtcs (ie. before cleaning up old framebuffers using
 * drm_atomic_helper_cleanup_planes()). It will only wait on crtcs where the
 * framebuffers have actually changed to optimize for the legacy cursor and
 * plane update use-case.
 */
void
drm_atomic_helper_wait_for_vblanks(struct drm_device *dev,
                struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        int i, ret;
        unsigned crtc_mask = 0;

         /*
          * Legacy cursor ioctls are completely unsynced, and userspace
          * relies on that (by doing tons of cursor updates).
          */
        if (old_state->legacy_cursor_update)
                return;

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                struct drm_crtc_state *new_crtc_state = crtc->state;

                if (!new_crtc_state->active || !new_crtc_state->planes_changed)
                        continue;

                ret = drm_crtc_vblank_get(crtc);
                if (ret != 0)
                        continue;

                crtc_mask |= drm_crtc_mask(crtc);
                old_state->crtcs[i].last_vblank_count = drm_crtc_vblank_count(crtc);
        }

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                if (!(crtc_mask & drm_crtc_mask(crtc)))
                        continue;

                ret = wait_event_timeout(dev->vblank[i].queue,
                                old_state->crtcs[i].last_vblank_count !=
                                        drm_crtc_vblank_count(crtc),
                                msecs_to_jiffies(50));

                WARN(!ret, "[CRTC:%d] vblank wait timed out\n", crtc->base.id);

                drm_crtc_vblank_put(crtc);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_wait_for_vblanks);

/**
 * drm_atomic_helper_commit_tail - commit atomic update to hardware
 * @old_state: atomic state object with old state structures
 *
 * This is the default implemenation for the ->atomic_commit_tail() hook of the
 * &drm_mode_config_helper_funcs vtable.
 *
 * Note that the default ordering of how the various stages are called is to
 * match the legacy modeset helper library closest. One peculiarity of that is
 * that it doesn't mesh well with runtime PM at all.
 *
 * For drivers supporting runtime PM the recommended sequence is instead ::
 *
 *     drm_atomic_helper_commit_modeset_disables(dev, old_state);
 *
 *     drm_atomic_helper_commit_modeset_enables(dev, old_state);
 *
 *     drm_atomic_helper_commit_planes(dev, old_state,
 *                                     DRM_PLANE_COMMIT_ACTIVE_ONLY);
 *
 * for committing the atomic update to hardware.  See the kerneldoc entries for
 * these three functions for more details.
 */
void drm_atomic_helper_commit_tail(struct drm_atomic_state *old_state)
{
        struct drm_device *dev = old_state->dev;

        drm_atomic_helper_commit_modeset_disables(dev, old_state);

        drm_atomic_helper_commit_planes(dev, old_state, 0);

        drm_atomic_helper_commit_modeset_enables(dev, old_state);

        drm_atomic_helper_commit_hw_done(old_state);

        drm_atomic_helper_wait_for_vblanks(dev, old_state);

        drm_atomic_helper_cleanup_planes(dev, old_state);
}
EXPORT_SYMBOL(drm_atomic_helper_commit_tail);

static void commit_tail(struct drm_atomic_state *old_state)
{
        struct drm_device *dev = old_state->dev;
        struct drm_mode_config_helper_funcs *funcs;

        funcs = dev->mode_config.helper_private;

        drm_atomic_helper_wait_for_fences(dev, old_state, false);

        drm_atomic_helper_wait_for_dependencies(old_state);

        if (funcs && funcs->atomic_commit_tail)
                funcs->atomic_commit_tail(old_state);
        else
                drm_atomic_helper_commit_tail(old_state);

        drm_atomic_helper_commit_cleanup_done(old_state);

        drm_atomic_state_put(old_state);
}

static void commit_work(struct work_struct *work)
{
        struct drm_atomic_state *state = container_of(work,
                                                      struct drm_atomic_state,
                                                      commit_work);
        commit_tail(state);
}

/**
 * drm_atomic_helper_commit - commit validated state object
 * @dev: DRM device
 * @state: the driver state object
 * @nonblock: whether nonblocking behavior is requested.
 *
 * This function commits a with drm_atomic_helper_check() pre-validated state
 * object. This can still fail when e.g. the framebuffer reservation fails. This
 * function implements nonblocking commits, using
 * drm_atomic_helper_setup_commit() and related functions.
 *
 * Committing the actual hardware state is done through the
 * ->atomic_commit_tail() callback of the &drm_mode_config_helper_funcs vtable,
 * or it's default implementation drm_atomic_helper_commit_tail().
 *
 * RETURNS:
 * Zero for success or -errno.
 */
int drm_atomic_helper_commit(struct drm_device *dev,
                             struct drm_atomic_state *state,
                             bool nonblock)
{
        int ret;

        ret = drm_atomic_helper_setup_commit(state, nonblock);
        if (ret)
                return ret;

        INIT_WORK(&state->commit_work, commit_work);

        ret = drm_atomic_helper_prepare_planes(dev, state);
        if (ret)
                return ret;

        if (!nonblock) {
                ret = drm_atomic_helper_wait_for_fences(dev, state, true);
                if (ret)
                        return ret;
        }

        /*
         * This is the point of no return - everything below never fails except
         * when the hw goes bonghits. Which means we can commit the new state on
         * the software side now.
         */

        drm_atomic_helper_swap_state(state, true);

        /*
         * Everything below can be run asynchronously without the need to grab
         * any modeset locks at all under one condition: It must be guaranteed
         * that the asynchronous work has either been cancelled (if the driver
         * supports it, which at least requires that the framebuffers get
         * cleaned up with drm_atomic_helper_cleanup_planes()) or completed
         * before the new state gets committed on the software side with
         * drm_atomic_helper_swap_state().
         *
         * This scheme allows new atomic state updates to be prepared and
         * checked in parallel to the asynchronous completion of the previous
         * update. Which is important since compositors need to figure out the
         * composition of the next frame right after having submitted the
         * current layout.
         *
         * NOTE: Commit work has multiple phases, first hardware commit, then
         * cleanup. We want them to overlap, hence need system_unbound_wq to
         * make sure work items don't artifically stall on each another.
         */

        drm_atomic_state_get(state);
        if (nonblock)
                queue_work(system_unbound_wq, &state->commit_work);
        else
                commit_tail(state);

        return 0;
}
EXPORT_SYMBOL(drm_atomic_helper_commit);

/**
 * DOC: implementing nonblocking commit
 *
 * Nonblocking atomic commits have to be implemented in the following sequence:
 *
 * 1. Run drm_atomic_helper_prepare_planes() first. This is the only function
 * which commit needs to call which can fail, so we want to run it first and
 * synchronously.
 *
 * 2. Synchronize with any outstanding nonblocking commit worker threads which
 * might be affected the new state update. This can be done by either cancelling
 * or flushing the work items, depending upon whether the driver can deal with
 * cancelled updates. Note that it is important to ensure that the framebuffer
 * cleanup is still done when cancelling.
 *
 * Asynchronous workers need to have sufficient parallelism to be able to run
 * different atomic commits on different CRTCs in parallel. The simplest way to
 * achive this is by running them on the &system_unbound_wq work queue. Note
 * that drivers are not required to split up atomic commits and run an
 * individual commit in parallel - userspace is supposed to do that if it cares.
 * But it might be beneficial to do that for modesets, since those necessarily
 * must be done as one global operation, and enabling or disabling a CRTC can
 * take a long time. But even that is not required.
 *
 * 3. The software state is updated synchronously with
 * drm_atomic_helper_swap_state(). Doing this under the protection of all modeset
 * locks means concurrent callers never see inconsistent state. And doing this
 * while it's guaranteed that no relevant nonblocking worker runs means that
 * nonblocking workers do not need grab any locks. Actually they must not grab
 * locks, for otherwise the work flushing will deadlock.
 *
 * 4. Schedule a work item to do all subsequent steps, using the split-out
 * commit helpers: a) pre-plane commit b) plane commit c) post-plane commit and
 * then cleaning up the framebuffers after the old framebuffer is no longer
 * being displayed.
 *
 * The above scheme is implemented in the atomic helper libraries in
 * drm_atomic_helper_commit() using a bunch of helper functions. See
 * drm_atomic_helper_setup_commit() for a starting point.
 */

static int stall_checks(struct drm_crtc *crtc, bool nonblock)
{
        struct drm_crtc_commit *commit, *stall_commit = NULL;
        bool completed = true;
        int i;
        long ret = 0;

        spin_lock(&crtc->commit_lock);
        i = 0;
        list_for_each_entry(commit, &crtc->commit_list, commit_entry) {
                if (i == 0) {
                        completed = try_wait_for_completion(&commit->flip_done);
                        /* Userspace is not allowed to get ahead of the previous
                         * commit with nonblocking ones. */
                        if (!completed && nonblock) {
                                spin_unlock(&crtc->commit_lock);
                                return -EBUSY;
                        }
                } else if (i == 1) {
                        stall_commit = commit;
                        drm_crtc_commit_get(stall_commit);
                        break;
                }

                i++;
        }
        spin_unlock(&crtc->commit_lock);

        if (!stall_commit)
                return 0;

        /* We don't want to let commits get ahead of cleanup work too much,
         * stalling on 2nd previous commit means triple-buffer won't ever stall.
         */
        ret = wait_for_completion_interruptible_timeout(&stall_commit->cleanup_done,
                                                        10*HZ);
        if (ret == 0)
                DRM_ERROR("[CRTC:%d:%s] cleanup_done timed out\n",
                          crtc->base.id, crtc->name);

        drm_crtc_commit_put(stall_commit);

        return ret < 0 ? ret : 0;
}

void release_crtc_commit(struct completion *completion)
{
        struct drm_crtc_commit *commit = container_of(completion,
                                                      typeof(*commit),
                                                      flip_done);

        drm_crtc_commit_put(commit);
}

/**
 * drm_atomic_helper_setup_commit - setup possibly nonblocking commit
 * @state: new modeset state to be committed
 * @nonblock: whether nonblocking behavior is requested.
 *
 * This function prepares @state to be used by the atomic helper's support for
 * nonblocking commits. Drivers using the nonblocking commit infrastructure
 * should always call this function from their ->atomic_commit hook.
 *
 * To be able to use this support drivers need to use a few more helper
 * functions. drm_atomic_helper_wait_for_dependencies() must be called before
 * actually committing the hardware state, and for nonblocking commits this call
 * must be placed in the async worker. See also drm_atomic_helper_swap_state()
 * and it's stall parameter, for when a driver's commit hooks look at the
 * ->state pointers of &struct drm_crtc, &drm_plane or &drm_connector directly.
 *
 * Completion of the hardware commit step must be signalled using
 * drm_atomic_helper_commit_hw_done(). After this step the driver is not allowed
 * to read or change any permanent software or hardware modeset state. The only
 * exception is state protected by other means than &drm_modeset_lock locks.
 * Only the free standing @state with pointers to the old state structures can
 * be inspected, e.g. to clean up old buffers using
 * drm_atomic_helper_cleanup_planes().
 *
 * At the very end, before cleaning up @state drivers must call
 * drm_atomic_helper_commit_cleanup_done().
 *
 * This is all implemented by in drm_atomic_helper_commit(), giving drivers a
 * complete and esay-to-use default implementation of the atomic_commit() hook.
 *
 * The tracking of asynchronously executed and still pending commits is done
 * using the core structure &drm_crtc_commit.
 *
 * By default there's no need to clean up resources allocated by this function
 * explicitly: drm_atomic_state_default_clear() will take care of that
 * automatically.
 *
 * Returns:
 *
 * 0 on success. -EBUSY when userspace schedules nonblocking commits too fast,
 * -ENOMEM on allocation failures and -EINTR when a signal is pending.
 */
int drm_atomic_helper_setup_commit(struct drm_atomic_state *state,
                                   bool nonblock)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_crtc_commit *commit;
        int i, ret;

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                commit = kzalloc(sizeof(*commit), GFP_KERNEL);
                if (!commit)
                        return -ENOMEM;

                init_completion(&commit->flip_done);
                init_completion(&commit->hw_done);
                init_completion(&commit->cleanup_done);
                INIT_LIST_HEAD(&commit->commit_entry);
                kref_init(&commit->ref);
                commit->crtc = crtc;

                state->crtcs[i].commit = commit;

                ret = stall_checks(crtc, nonblock);
                if (ret)
                        return ret;

                /* Drivers only send out events when at least either current or
                 * new CRTC state is active. Complete right away if everything
                 * stays off. */
                if (!crtc->state->active && !crtc_state->active) {
                        complete_all(&commit->flip_done);
                        continue;
                }

                /* Legacy cursor updates are fully unsynced. */
                if (state->legacy_cursor_update) {
                        complete_all(&commit->flip_done);
                        continue;
                }

                if (!crtc_state->event) {
                        commit->event = kzalloc(sizeof(*commit->event),
                                                GFP_KERNEL);
                        if (!commit->event)
                                return -ENOMEM;

                        crtc_state->event = commit->event;
                }

                crtc_state->event->base.completion = &commit->flip_done;
                crtc_state->event->base.completion_release = release_crtc_commit;
                drm_crtc_commit_get(commit);
        }

        return 0;
}
EXPORT_SYMBOL(drm_atomic_helper_setup_commit);


static struct drm_crtc_commit *preceeding_commit(struct drm_crtc *crtc)
{
        struct drm_crtc_commit *commit;
        int i = 0;

        list_for_each_entry(commit, &crtc->commit_list, commit_entry) {
                /* skip the first entry, that's the current commit */
                if (i == 1)
                        return commit;
                i++;
        }

        return NULL;
}

/**
 * drm_atomic_helper_wait_for_dependencies - wait for required preceeding commits
 * @old_state: atomic state object with old state structures
 *
 * This function waits for all preceeding commits that touch the same CRTC as
 * @old_state to both be committed to the hardware (as signalled by
 * drm_atomic_helper_commit_hw_done) and executed by the hardware (as signalled
 * by calling drm_crtc_vblank_send_event on the event member of
 * &drm_crtc_state).
 *
 * This is part of the atomic helper support for nonblocking commits, see
 * drm_atomic_helper_setup_commit() for an overview.
 */
void drm_atomic_helper_wait_for_dependencies(struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_crtc_commit *commit;
        int i;
        long ret;

        for_each_crtc_in_state(old_state, crtc, crtc_state, i) {
                spin_lock(&crtc->commit_lock);
                commit = preceeding_commit(crtc);
                if (commit)
                        drm_crtc_commit_get(commit);
                spin_unlock(&crtc->commit_lock);

                if (!commit)
                        continue;

                ret = wait_for_completion_timeout(&commit->hw_done,
                                                  10*HZ);
                if (ret == 0)
                        DRM_ERROR("[CRTC:%d:%s] hw_done timed out\n",
                                  crtc->base.id, crtc->name);

                /* Currently no support for overwriting flips, hence
                 * stall for previous one to execute completely. */
                ret = wait_for_completion_timeout(&commit->flip_done,
                                                  10*HZ);
                if (ret == 0)
                        DRM_ERROR("[CRTC:%d:%s] flip_done timed out\n",
                                  crtc->base.id, crtc->name);

                drm_crtc_commit_put(commit);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_wait_for_dependencies);

/**
 * drm_atomic_helper_commit_hw_done - setup possible nonblocking commit
 * @old_state: atomic state object with old state structures
 *
 * This function is used to signal completion of the hardware commit step. After
 * this step the driver is not allowed to read or change any permanent software
 * or hardware modeset state. The only exception is state protected by other
 * means than &drm_modeset_lock locks.
 *
 * Drivers should try to postpone any expensive or delayed cleanup work after
 * this function is called.
 *
 * This is part of the atomic helper support for nonblocking commits, see
 * drm_atomic_helper_setup_commit() for an overview.
 */
void drm_atomic_helper_commit_hw_done(struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_crtc_commit *commit;
        int i;

        for_each_crtc_in_state(old_state, crtc, crtc_state, i) {
                commit = old_state->crtcs[i].commit;
                if (!commit)
                        continue;

                /* backend must have consumed any event by now */
                WARN_ON(crtc->state->event);
                spin_lock(&crtc->commit_lock);
                complete_all(&commit->hw_done);
                spin_unlock(&crtc->commit_lock);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_commit_hw_done);

/**
 * drm_atomic_helper_commit_cleanup_done - signal completion of commit
 * @old_state: atomic state object with old state structures
 *
 * This signals completion of the atomic update @old_state, including any
 * cleanup work. If used, it must be called right before calling
 * drm_atomic_state_put().
 *
 * This is part of the atomic helper support for nonblocking commits, see
 * drm_atomic_helper_setup_commit() for an overview.
 */
void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *old_state)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_crtc_commit *commit;
        int i;
        long ret;

        for_each_crtc_in_state(old_state, crtc, crtc_state, i) {
                commit = old_state->crtcs[i].commit;
                if (WARN_ON(!commit))
                        continue;

                spin_lock(&crtc->commit_lock);
                complete_all(&commit->cleanup_done);
                WARN_ON(!try_wait_for_completion(&commit->hw_done));

                /* commit_list borrows our reference, need to remove before we
                 * clean up our drm_atomic_state. But only after it actually
                 * completed, otherwise subsequent commits won't stall properly. */
                if (try_wait_for_completion(&commit->flip_done))
                        goto del_commit;

                spin_unlock(&crtc->commit_lock);

                /* We must wait for the vblank event to signal our completion
                 * before releasing our reference, since the vblank work does
                 * not hold a reference of its own. */
                ret = wait_for_completion_timeout(&commit->flip_done,
                                                  10*HZ);
                if (ret == 0)
                        DRM_ERROR("[CRTC:%d:%s] flip_done timed out\n",
                                  crtc->base.id, crtc->name);

                spin_lock(&crtc->commit_lock);
del_commit:
                list_del(&commit->commit_entry);
                spin_unlock(&crtc->commit_lock);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_commit_cleanup_done);

/**
 * drm_atomic_helper_prepare_planes - prepare plane resources before commit
 * @dev: DRM device
 * @state: atomic state object with new state structures
 *
 * This function prepares plane state, specifically framebuffers, for the new
 * configuration. If any failure is encountered this function will call
 * ->cleanup_fb on any already successfully prepared framebuffer.
 *
 * Returns:
 * 0 on success, negative error code on failure.
 */
int drm_atomic_helper_prepare_planes(struct drm_device *dev,
                                     struct drm_atomic_state *state)
{
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int ret, i, j;

        for_each_plane_in_state(state, plane, plane_state, i) {
                const struct drm_plane_helper_funcs *funcs;

                funcs = plane->helper_private;

                if (funcs->prepare_fb) {
                        ret = funcs->prepare_fb(plane, plane_state);
                        if (ret)
                                goto fail;
                }
        }

        return 0;

fail:
        for_each_plane_in_state(state, plane, plane_state, j) {
                const struct drm_plane_helper_funcs *funcs;

                if (j >= i)
                        continue;

                funcs = plane->helper_private;

                if (funcs->cleanup_fb)
                        funcs->cleanup_fb(plane, plane_state);
        }

        return ret;
}
EXPORT_SYMBOL(drm_atomic_helper_prepare_planes);

static bool plane_crtc_active(const struct drm_plane_state *state)
{
        return state->crtc && state->crtc->state->active;
}

/**
 * drm_atomic_helper_commit_planes - commit plane state
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 * @flags: flags for committing plane state
 *
 * This function commits the new plane state using the plane and atomic helper
 * functions for planes and crtcs. It assumes that the atomic state has already
 * been pushed into the relevant object state pointers, since this step can no
 * longer fail.
 *
 * It still requires the global state object @old_state to know which planes and
 * crtcs need to be updated though.
 *
 * Note that this function does all plane updates across all CRTCs in one step.
 * If the hardware can't support this approach look at
 * drm_atomic_helper_commit_planes_on_crtc() instead.
 *
 * Plane parameters can be updated by applications while the associated CRTC is
 * disabled. The DRM/KMS core will store the parameters in the plane state,
 * which will be available to the driver when the CRTC is turned on. As a result
 * most drivers don't need to be immediately notified of plane updates for a
 * disabled CRTC.
 *
 * Unless otherwise needed, drivers are advised to set the ACTIVE_ONLY flag in
 * @flags in order not to receive plane update notifications related to a
 * disabled CRTC. This avoids the need to manually ignore plane updates in
 * driver code when the driver and/or hardware can't or just don't need to deal
 * with updates on disabled CRTCs, for example when supporting runtime PM.
 *
 * Drivers may set the NO_DISABLE_AFTER_MODESET flag in @flags if the relevant
 * display controllers require to disable a CRTC's planes when the CRTC is
 * disabled. This function would skip the ->atomic_disable call for a plane if
 * the CRTC of the old plane state needs a modesetting operation. Of course,
 * the drivers need to disable the planes in their CRTC disable callbacks
 * since no one else would do that.
 *
 * The drm_atomic_helper_commit() default implementation doesn't set the
 * ACTIVE_ONLY flag to most closely match the behaviour of the legacy helpers.
 * This should not be copied blindly by drivers.
 */
void drm_atomic_helper_commit_planes(struct drm_device *dev,
                                     struct drm_atomic_state *old_state,
                                     uint32_t flags)
{
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state;
        struct drm_plane *plane;
        struct drm_plane_state *old_plane_state;
        int i;
        bool active_only = flags & DRM_PLANE_COMMIT_ACTIVE_ONLY;
        bool no_disable = flags & DRM_PLANE_COMMIT_NO_DISABLE_AFTER_MODESET;

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                funcs = crtc->helper_private;

                if (!funcs || !funcs->atomic_begin)
                        continue;

                if (active_only && !crtc->state->active)
                        continue;

                funcs->atomic_begin(crtc, old_crtc_state);
        }

        for_each_plane_in_state(old_state, plane, old_plane_state, i) {
                const struct drm_plane_helper_funcs *funcs;
                bool disabling;

                funcs = plane->helper_private;

                if (!funcs)
                        continue;

                disabling = drm_atomic_plane_disabling(plane, old_plane_state);

                if (active_only) {
                        /*
                         * Skip planes related to inactive CRTCs. If the plane
                         * is enabled use the state of the current CRTC. If the
                         * plane is being disabled use the state of the old
                         * CRTC to avoid skipping planes being disabled on an
                         * active CRTC.
                         */
                        if (!disabling && !plane_crtc_active(plane->state))
                                continue;
                        if (disabling && !plane_crtc_active(old_plane_state))
                                continue;
                }

                /*
                 * Special-case disabling the plane if drivers support it.
                 */
                if (disabling && funcs->atomic_disable) {
                        struct drm_crtc_state *crtc_state;

                        crtc_state = old_plane_state->crtc->state;

                        if (drm_atomic_crtc_needs_modeset(crtc_state) &&
                            no_disable)
                                continue;

                        funcs->atomic_disable(plane, old_plane_state);
                } else if (plane->state->crtc || disabling) {
                        funcs->atomic_update(plane, old_plane_state);
                }
        }

        for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
                const struct drm_crtc_helper_funcs *funcs;

                funcs = crtc->helper_private;

                if (!funcs || !funcs->atomic_flush)
                        continue;

                if (active_only && !crtc->state->active)
                        continue;

                funcs->atomic_flush(crtc, old_crtc_state);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_commit_planes);

/**
 * drm_atomic_helper_commit_planes_on_crtc - commit plane state for a crtc
 * @old_crtc_state: atomic state object with the old crtc state
 *
 * This function commits the new plane state using the plane and atomic helper
 * functions for planes on the specific crtc. It assumes that the atomic state
 * has already been pushed into the relevant object state pointers, since this
 * step can no longer fail.
 *
 * This function is useful when plane updates should be done crtc-by-crtc
 * instead of one global step like drm_atomic_helper_commit_planes() does.
 *
 * This function can only be savely used when planes are not allowed to move
 * between different CRTCs because this function doesn't handle inter-CRTC
 * depencies. Callers need to ensure that either no such depencies exist,
 * resolve them through ordering of commit calls or through some other means.
 */
void
drm_atomic_helper_commit_planes_on_crtc(struct drm_crtc_state *old_crtc_state)
{
        const struct drm_crtc_helper_funcs *crtc_funcs;
        struct drm_crtc *crtc = old_crtc_state->crtc;
        struct drm_atomic_state *old_state = old_crtc_state->state;
        struct drm_plane *plane;
        unsigned plane_mask;

        plane_mask = old_crtc_state->plane_mask;
        plane_mask |= crtc->state->plane_mask;

        crtc_funcs = crtc->helper_private;
        if (crtc_funcs && crtc_funcs->atomic_begin)
                crtc_funcs->atomic_begin(crtc, old_crtc_state);

        drm_for_each_plane_mask(plane, crtc->dev, plane_mask) {
                struct drm_plane_state *old_plane_state =
                        drm_atomic_get_existing_plane_state(old_state, plane);
                const struct drm_plane_helper_funcs *plane_funcs;

                plane_funcs = plane->helper_private;

                if (!old_plane_state || !plane_funcs)
                        continue;

                WARN_ON(plane->state->crtc && plane->state->crtc != crtc);

                if (drm_atomic_plane_disabling(plane, old_plane_state) &&
                    plane_funcs->atomic_disable)
                        plane_funcs->atomic_disable(plane, old_plane_state);
                else if (plane->state->crtc ||
                         drm_atomic_plane_disabling(plane, old_plane_state))
                        plane_funcs->atomic_update(plane, old_plane_state);
        }

        if (crtc_funcs && crtc_funcs->atomic_flush)
                crtc_funcs->atomic_flush(crtc, old_crtc_state);
}
EXPORT_SYMBOL(drm_atomic_helper_commit_planes_on_crtc);

/**
 * drm_atomic_helper_disable_planes_on_crtc - helper to disable CRTC's planes
 * @old_crtc_state: atomic state object with the old CRTC state
 * @atomic: if set, synchronize with CRTC's atomic_begin/flush hooks
 *
 * Disables all planes associated with the given CRTC. This can be
 * used for instance in the CRTC helper atomic_disable callback to disable
 * all planes.
 *
 * If the atomic-parameter is set the function calls the CRTC's
 * atomic_begin hook before and atomic_flush hook after disabling the
 * planes.
 *
 * It is a bug to call this function without having implemented the
 * ->atomic_disable() plane hook.
 */
void
drm_atomic_helper_disable_planes_on_crtc(struct drm_crtc_state *old_crtc_state,
                                         bool atomic)
{
        struct drm_crtc *crtc = old_crtc_state->crtc;
        const struct drm_crtc_helper_funcs *crtc_funcs =
                crtc->helper_private;
        struct drm_plane *plane;

        if (atomic && crtc_funcs && crtc_funcs->atomic_begin)
                crtc_funcs->atomic_begin(crtc, NULL);

        drm_atomic_crtc_state_for_each_plane(plane, old_crtc_state) {
                const struct drm_plane_helper_funcs *plane_funcs =
                        plane->helper_private;

                if (!plane_funcs)
                        continue;

                WARN_ON(!plane_funcs->atomic_disable);
                if (plane_funcs->atomic_disable)
                        plane_funcs->atomic_disable(plane, NULL);
        }

        if (atomic && crtc_funcs && crtc_funcs->atomic_flush)
                crtc_funcs->atomic_flush(crtc, NULL);
}
EXPORT_SYMBOL(drm_atomic_helper_disable_planes_on_crtc);

/**
 * drm_atomic_helper_cleanup_planes - cleanup plane resources after commit
 * @dev: DRM device
 * @old_state: atomic state object with old state structures
 *
 * This function cleans up plane state, specifically framebuffers, from the old
 * configuration. Hence the old configuration must be perserved in @old_state to
 * be able to call this function.
 *
 * This function must also be called on the new state when the atomic update
 * fails at any point after calling drm_atomic_helper_prepare_planes().
 */
void drm_atomic_helper_cleanup_planes(struct drm_device *dev,
                                      struct drm_atomic_state *old_state)
{
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        int i;

        for_each_plane_in_state(old_state, plane, plane_state, i) {
                const struct drm_plane_helper_funcs *funcs;

                funcs = plane->helper_private;

                if (funcs->cleanup_fb)
                        funcs->cleanup_fb(plane, plane_state);
        }
}
EXPORT_SYMBOL(drm_atomic_helper_cleanup_planes);

/**
 * drm_atomic_helper_swap_state - store atomic state into current sw state
 * @state: atomic state
 * @stall: stall for proceeding commits
 *
 * This function stores the atomic state into the current state pointers in all
 * driver objects. It should be called after all failing steps have been done
 * and succeeded, but before the actual hardware state is committed.
 *
 * For cleanup and error recovery the current state for all changed objects will
 * be swaped into @state.
 *
 * With that sequence it fits perfectly into the plane prepare/cleanup sequence:
 *
 * 1. Call drm_atomic_helper_prepare_planes() with the staged atomic state.
 *
 * 2. Do any other steps that might fail.
 *
 * 3. Put the staged state into the current state pointers with this function.
 *
 * 4. Actually commit the hardware state.
 *
 * 5. Call drm_atomic_helper_cleanup_planes() with @state, which since step 3
 * contains the old state. Also do any other cleanup required with that state.
 *
 * @stall must be set when nonblocking commits for this driver directly access
 * the ->state pointer of &drm_plane, &drm_crtc or &drm_connector. With the
 * current atomic helpers this is almost always the case, since the helpers
 * don't pass the right state structures to the callbacks.
 */
void drm_atomic_helper_swap_state(struct drm_atomic_state *state,
                                  bool stall)
{
        int i;
        long ret;
        struct drm_connector *connector;
        struct drm_connector_state *conn_state;
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_plane *plane;
        struct drm_plane_state *plane_state;
        struct drm_crtc_commit *commit;

        if (stall) {
                for_each_crtc_in_state(state, crtc, crtc_state, i) {
                        spin_lock(&crtc->commit_lock);
                        commit = list_first_entry_or_null(&crtc->commit_list,
                                        struct drm_crtc_commit, commit_entry);
                        if (commit)
                                drm_crtc_commit_get(commit);
                        spin_unlock(&crtc->commit_lock);

                        if (!commit)
                                continue;

                        ret = wait_for_completion_timeout(&commit->hw_done,
                                                          10*HZ);
                        if (ret == 0)
                                DRM_ERROR("[CRTC:%d:%s] hw_done timed out\n",
                                          crtc->base.id, crtc->name);
                        drm_crtc_commit_put(commit);
                }
        }

        for_each_connector_in_state(state, connector, conn_state, i) {
                connector->state->state = state;
                swap(state->connectors[i].state, connector->state);
                connector->state->state = NULL;
        }

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                crtc->state->state = state;
                swap(state->crtcs[i].state, crtc->state);
                crtc->state->state = NULL;

                if (state->crtcs[i].commit) {
                        spin_lock(&crtc->commit_lock);
                        list_add(&state->crtcs[i].commit->commit_entry,
                                 &crtc->commit_list);
                        spin_unlock(&crtc->commit_lock);

                        state->crtcs[i].commit->event = NULL;
                }
        }

        for_each_plane_in_state(state, plane, plane_state, i) {
                plane->state->state = state;
                swap(state->planes[i].state, plane->state);
                plane->state->state = NULL;
        }
}
EXPORT_SYMBOL(drm_atomic_helper_swap_state);

/**
 * drm_atomic_helper_update_plane - Helper for primary plane update using atomic
 * @plane: plane object to update
 * @crtc: owning CRTC of owning plane
 * @fb: framebuffer to flip onto plane
 * @crtc_x: x offset of primary plane on crtc
 * @crtc_y: y offset of primary plane on crtc
 * @crtc_w: width of primary plane rectangle on crtc
 * @crtc_h: height of primary plane rectangle on crtc
 * @src_x: x offset of @fb for panning
 * @src_y: y offset of @fb for panning
 * @src_w: width of source rectangle in @fb
 * @src_h: height of source rectangle in @fb
 *
 * Provides a default plane update handler using the atomic driver interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int drm_atomic_helper_update_plane(struct drm_plane *plane,
                                   struct drm_crtc *crtc,
                                   struct drm_framebuffer *fb,
                                   int crtc_x, int crtc_y,
                                   unsigned int crtc_w, unsigned int crtc_h,
                                   uint32_t src_x, uint32_t src_y,
                                   uint32_t src_w, uint32_t src_h)
{
        struct drm_atomic_state *state;
        struct drm_plane_state *plane_state;
        int ret = 0;

        state = drm_atomic_state_alloc(plane->dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
retry:
        plane_state = drm_atomic_get_plane_state(state, plane);
        if (IS_ERR(plane_state)) {
                ret = PTR_ERR(plane_state);
                goto fail;
        }

        ret = drm_atomic_set_crtc_for_plane(plane_state, crtc);
        if (ret != 0)
                goto fail;
        drm_atomic_set_fb_for_plane(plane_state, fb);
        plane_state->crtc_x = crtc_x;
        plane_state->crtc_y = crtc_y;
        plane_state->crtc_w = crtc_w;
        plane_state->crtc_h = crtc_h;
        plane_state->src_x = src_x;
        plane_state->src_y = src_y;
        plane_state->src_w = src_w;
        plane_state->src_h = src_h;

        if (plane == crtc->cursor)
                state->legacy_cursor_update = true;

        ret = drm_atomic_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_put(state);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        /*
         * Someone might have exchanged the framebuffer while we dropped locks
         * in the backoff code. We need to fix up the fb refcount tracking the
         * core does for us.
         */
        plane->old_fb = plane->fb;

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_update_plane);

/**
 * drm_atomic_helper_disable_plane - Helper for primary plane disable using * atomic
 * @plane: plane to disable
 *
 * Provides a default plane disable handler using the atomic driver interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int drm_atomic_helper_disable_plane(struct drm_plane *plane)
{
        struct drm_atomic_state *state;
        struct drm_plane_state *plane_state;
        int ret = 0;

        /*
         * FIXME: Without plane->crtc set we can't get at the implicit legacy
         * acquire context. The real fix will be to wire the acquire ctx through
         * everywhere we need it, but meanwhile prevent chaos by just skipping
         * this noop. The critical case is the cursor ioctls which a) only grab
         * crtc/cursor-plane locks (so we need the crtc to get at the right
         * acquire context) and b) can try to disable the plane multiple times.
         */
        if (!plane->crtc)
                return 0;

        state = drm_atomic_state_alloc(plane->dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(plane->crtc);
retry:
        plane_state = drm_atomic_get_plane_state(state, plane);
        if (IS_ERR(plane_state)) {
                ret = PTR_ERR(plane_state);
                goto fail;
        }

        if (plane_state->crtc && (plane == plane->crtc->cursor))
                plane_state->state->legacy_cursor_update = true;

        ret = __drm_atomic_helper_disable_plane(plane, plane_state);
        if (ret != 0)
                goto fail;

        ret = drm_atomic_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_put(state);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        /*
         * Someone might have exchanged the framebuffer while we dropped locks
         * in the backoff code. We need to fix up the fb refcount tracking the
         * core does for us.
         */
        plane->old_fb = plane->fb;

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_disable_plane);

/* just used from fb-helper and atomic-helper: */
int __drm_atomic_helper_disable_plane(struct drm_plane *plane,
                struct drm_plane_state *plane_state)
{
        int ret;

        ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
        if (ret != 0)
                return ret;

        drm_atomic_set_fb_for_plane(plane_state, NULL);
        plane_state->crtc_x = 0;
        plane_state->crtc_y = 0;
        plane_state->crtc_w = 0;
        plane_state->crtc_h = 0;
        plane_state->src_x = 0;
        plane_state->src_y = 0;
        plane_state->src_w = 0;
        plane_state->src_h = 0;

        return 0;
}

static int update_output_state(struct drm_atomic_state *state,
                               struct drm_mode_set *set)
{
        struct drm_device *dev = set->crtc->dev;
        struct drm_crtc *crtc;
        struct drm_crtc_state *crtc_state;
        struct drm_connector *connector;
        struct drm_connector_state *conn_state;
        int ret, i;

        ret = drm_modeset_lock(&dev->mode_config.connection_mutex,
                               state->acquire_ctx);
        if (ret)
                return ret;

        /* First disable all connectors on the target crtc. */
        ret = drm_atomic_add_affected_connectors(state, set->crtc);
        if (ret)
                return ret;

        for_each_connector_in_state(state, connector, conn_state, i) {
                if (conn_state->crtc == set->crtc) {
                        ret = drm_atomic_set_crtc_for_connector(conn_state,
                                                                NULL);
                        if (ret)
                                return ret;
                }
        }

        /* Then set all connectors from set->connectors on the target crtc */
        for (i = 0; i < set->num_connectors; i++) {
                conn_state = drm_atomic_get_connector_state(state,
                                                            set->connectors[i]);
                if (IS_ERR(conn_state))
                        return PTR_ERR(conn_state);

                ret = drm_atomic_set_crtc_for_connector(conn_state,
                                                        set->crtc);
                if (ret)
                        return ret;
        }

        for_each_crtc_in_state(state, crtc, crtc_state, i) {
                /* Don't update ->enable for the CRTC in the set_config request,
                 * since a mismatch would indicate a bug in the upper layers.
                 * The actual modeset code later on will catch any
                 * inconsistencies here. */
                if (crtc == set->crtc)
                        continue;

                if (!crtc_state->connector_mask) {
                        ret = drm_atomic_set_mode_prop_for_crtc(crtc_state,
                                                                NULL);
                        if (ret < 0)
                                return ret;

                        crtc_state->active = false;
                }
        }

        return 0;
}

/**
 * drm_atomic_helper_set_config - set a new config from userspace
 * @set: mode set configuration
 *
 * Provides a default crtc set_config handler using the atomic driver interface.
 *
 * Returns:
 * Returns 0 on success, negative errno numbers on failure.
 */
int drm_atomic_helper_set_config(struct drm_mode_set *set)
{
        struct drm_atomic_state *state;
        struct drm_crtc *crtc = set->crtc;
        int ret = 0;

        state = drm_atomic_state_alloc(crtc->dev);
        if (!state)
                return -ENOMEM;

        state->legacy_set_config = true;
        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
retry:
        ret = __drm_atomic_helper_set_config(set, state);
        if (ret != 0)
                goto fail;

        ret = drm_atomic_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_put(state);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        /*
         * Someone might have exchanged the framebuffer while we dropped locks
         * in the backoff code. We need to fix up the fb refcount tracking the
         * core does for us.
         */
        crtc->primary->old_fb = crtc->primary->fb;

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_set_config);

/* just used from fb-helper and atomic-helper: */
int __drm_atomic_helper_set_config(struct drm_mode_set *set,
                struct drm_atomic_state *state)
{
        struct drm_crtc_state *crtc_state;
        struct drm_plane_state *primary_state;
        struct drm_crtc *crtc = set->crtc;
        int hdisplay, vdisplay;
        int ret;

        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state))
                return PTR_ERR(crtc_state);

        primary_state = drm_atomic_get_plane_state(state, crtc->primary);
        if (IS_ERR(primary_state))
                return PTR_ERR(primary_state);

        if (!set->mode) {
                WARN_ON(set->fb);
                WARN_ON(set->num_connectors);

                ret = drm_atomic_set_mode_for_crtc(crtc_state, NULL);
                if (ret != 0)
                        return ret;

                crtc_state->active = false;

                ret = drm_atomic_set_crtc_for_plane(primary_state, NULL);
                if (ret != 0)
                        return ret;

                drm_atomic_set_fb_for_plane(primary_state, NULL);

                goto commit;
        }

        WARN_ON(!set->fb);
        WARN_ON(!set->num_connectors);

        ret = drm_atomic_set_mode_for_crtc(crtc_state, set->mode);
        if (ret != 0)
                return ret;

        crtc_state->active = true;

        ret = drm_atomic_set_crtc_for_plane(primary_state, crtc);
        if (ret != 0)
                return ret;

        drm_crtc_get_hv_timing(set->mode, &hdisplay, &vdisplay);

        drm_atomic_set_fb_for_plane(primary_state, set->fb);
        primary_state->crtc_x = 0;
        primary_state->crtc_y = 0;
        primary_state->crtc_w = hdisplay;
        primary_state->crtc_h = vdisplay;
        primary_state->src_x = set->x << 16;
        primary_state->src_y = set->y << 16;
        if (drm_rotation_90_or_270(primary_state->rotation)) {
                primary_state->src_w = vdisplay << 16;
                primary_state->src_h = hdisplay << 16;
        } else {
                primary_state->src_w = hdisplay << 16;
                primary_state->src_h = vdisplay << 16;
        }

commit:
        ret = update_output_state(state, set);
        if (ret)
                return ret;

        return 0;
}

/**
 * drm_atomic_helper_disable_all - disable all currently active outputs
 * @dev: DRM device
 * @ctx: lock acquisition context
 *
 * Loops through all connectors, finding those that aren't turned off and then
 * turns them off by setting their DPMS mode to OFF and deactivating the CRTC
 * that they are connected to.
 *
 * This is used for example in suspend/resume to disable all currently active
 * functions when suspending.
 *
 * Note that if callers haven't already acquired all modeset locks this might
 * return -EDEADLK, which must be handled by calling drm_modeset_backoff().
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 *
 * See also:
 * drm_atomic_helper_suspend(), drm_atomic_helper_resume()
 */
int drm_atomic_helper_disable_all(struct drm_device *dev,
                                  struct drm_modeset_acquire_ctx *ctx)
{
        struct drm_atomic_state *state;
        struct drm_connector *conn;
        struct drm_connector_list_iter conn_iter;
        int err;

        state = drm_atomic_state_alloc(dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = ctx;

        drm_connector_list_iter_get(dev, &conn_iter);
        drm_for_each_connector_iter(conn, &conn_iter) {
                struct drm_crtc *crtc = conn->state->crtc;
                struct drm_crtc_state *crtc_state;

                if (!crtc || conn->dpms != DRM_MODE_DPMS_ON)
                        continue;

                crtc_state = drm_atomic_get_crtc_state(state, crtc);
                if (IS_ERR(crtc_state)) {
                        err = PTR_ERR(crtc_state);
                        goto free;
                }

                crtc_state->active = false;
        }

        err = drm_atomic_commit(state);
free:
        drm_connector_list_iter_put(&conn_iter);
        drm_atomic_state_put(state);
        return err;
}
EXPORT_SYMBOL(drm_atomic_helper_disable_all);

/**
 * drm_atomic_helper_suspend - subsystem-level suspend helper
 * @dev: DRM device
 *
 * Duplicates the current atomic state, disables all active outputs and then
 * returns a pointer to the original atomic state to the caller. Drivers can
 * pass this pointer to the drm_atomic_helper_resume() helper upon resume to
 * restore the output configuration that was active at the time the system
 * entered suspend.
 *
 * Note that it is potentially unsafe to use this. The atomic state object
 * returned by this function is assumed to be persistent. Drivers must ensure
 * that this holds true. Before calling this function, drivers must make sure
 * to suspend fbdev emulation so that nothing can be using the device.
 *
 * Returns:
 * A pointer to a copy of the state before suspend on success or an ERR_PTR()-
 * encoded error code on failure. Drivers should store the returned atomic
 * state object and pass it to the drm_atomic_helper_resume() helper upon
 * resume.
 *
 * See also:
 * drm_atomic_helper_duplicate_state(), drm_atomic_helper_disable_all(),
 * drm_atomic_helper_resume()
 */
struct drm_atomic_state *drm_atomic_helper_suspend(struct drm_device *dev)
{
        struct drm_modeset_acquire_ctx ctx;
        struct drm_atomic_state *state;
        int err;

        drm_modeset_acquire_init(&ctx, 0);

retry:
        err = drm_modeset_lock_all_ctx(dev, &ctx);
        if (err < 0) {
                state = ERR_PTR(err);
                goto unlock;
        }

        state = drm_atomic_helper_duplicate_state(dev, &ctx);
        if (IS_ERR(state))
                goto unlock;

        err = drm_atomic_helper_disable_all(dev, &ctx);
        if (err < 0) {
                drm_atomic_state_put(state);
                state = ERR_PTR(err);
                goto unlock;
        }

unlock:
        if (PTR_ERR(state) == -EDEADLK) {
                drm_modeset_backoff(&ctx);
                goto retry;
        }

        drm_modeset_drop_locks(&ctx);
        drm_modeset_acquire_fini(&ctx);
        return state;
}
EXPORT_SYMBOL(drm_atomic_helper_suspend);

/**
 * drm_atomic_helper_resume - subsystem-level resume helper
 * @dev: DRM device
 * @state: atomic state to resume to
 *
 * Calls drm_mode_config_reset() to synchronize hardware and software states,
 * grabs all modeset locks and commits the atomic state object. This can be
 * used in conjunction with the drm_atomic_helper_suspend() helper to
 * implement suspend/resume for drivers that support atomic mode-setting.
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 *
 * See also:
 * drm_atomic_helper_suspend()
 */
int drm_atomic_helper_resume(struct drm_device *dev,
                             struct drm_atomic_state *state)
{
        struct drm_mode_config *config = &dev->mode_config;
        int err;

        drm_mode_config_reset(dev);
        drm_modeset_lock_all(dev);
        state->acquire_ctx = config->acquire_ctx;
        err = drm_atomic_commit(state);
        drm_modeset_unlock_all(dev);

        return err;
}
EXPORT_SYMBOL(drm_atomic_helper_resume);

/**
 * drm_atomic_helper_crtc_set_property - helper for crtc properties
 * @crtc: DRM crtc
 * @property: DRM property
 * @val: value of property
 *
 * Provides a default crtc set_property handler using the atomic driver
 * interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int
drm_atomic_helper_crtc_set_property(struct drm_crtc *crtc,
                                    struct drm_property *property,
                                    uint64_t val)
{
        struct drm_atomic_state *state;
        struct drm_crtc_state *crtc_state;
        int ret = 0;

        state = drm_atomic_state_alloc(crtc->dev);
        if (!state)
                return -ENOMEM;

        /* ->set_property is always called with all locks held. */
        state->acquire_ctx = crtc->dev->mode_config.acquire_ctx;
retry:
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                goto fail;
        }

        ret = drm_atomic_crtc_set_property(crtc, crtc_state,
                        property, val);
        if (ret)
                goto fail;

        ret = drm_atomic_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_put(state);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_set_property);

/**
 * drm_atomic_helper_plane_set_property - helper for plane properties
 * @plane: DRM plane
 * @property: DRM property
 * @val: value of property
 *
 * Provides a default plane set_property handler using the atomic driver
 * interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int
drm_atomic_helper_plane_set_property(struct drm_plane *plane,
                                    struct drm_property *property,
                                    uint64_t val)
{
        struct drm_atomic_state *state;
        struct drm_plane_state *plane_state;
        int ret = 0;

        state = drm_atomic_state_alloc(plane->dev);
        if (!state)
                return -ENOMEM;

        /* ->set_property is always called with all locks held. */
        state->acquire_ctx = plane->dev->mode_config.acquire_ctx;
retry:
        plane_state = drm_atomic_get_plane_state(state, plane);
        if (IS_ERR(plane_state)) {
                ret = PTR_ERR(plane_state);
                goto fail;
        }

        ret = drm_atomic_plane_set_property(plane, plane_state,
                        property, val);
        if (ret)
                goto fail;

        ret = drm_atomic_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_put(state);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_plane_set_property);

/**
 * drm_atomic_helper_connector_set_property - helper for connector properties
 * @connector: DRM connector
 * @property: DRM property
 * @val: value of property
 *
 * Provides a default connector set_property handler using the atomic driver
 * interface.
 *
 * RETURNS:
 * Zero on success, error code on failure
 */
int
drm_atomic_helper_connector_set_property(struct drm_connector *connector,
                                    struct drm_property *property,
                                    uint64_t val)
{
        struct drm_atomic_state *state;
        struct drm_connector_state *connector_state;
        int ret = 0;

        state = drm_atomic_state_alloc(connector->dev);
        if (!state)
                return -ENOMEM;

        /* ->set_property is always called with all locks held. */
        state->acquire_ctx = connector->dev->mode_config.acquire_ctx;
retry:
        connector_state = drm_atomic_get_connector_state(state, connector);
        if (IS_ERR(connector_state)) {
                ret = PTR_ERR(connector_state);
                goto fail;
        }

        ret = drm_atomic_connector_set_property(connector, connector_state,
                        property, val);
        if (ret)
                goto fail;

        ret = drm_atomic_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_put(state);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_set_property);

/**
 * drm_atomic_helper_page_flip - execute a legacy page flip
 * @crtc: DRM crtc
 * @fb: DRM framebuffer
 * @event: optional DRM event to signal upon completion
 * @flags: flip flags for non-vblank sync'ed updates
 *
 * Provides a default page flip implementation using the atomic driver interface.
 *
 * Note that for now so called async page flips (i.e. updates which are not
 * synchronized to vblank) are not supported, since the atomic interfaces have
 * no provisions for this yet.
 *
 * Returns:
 * Returns 0 on success, negative errno numbers on failure.
 */
int drm_atomic_helper_page_flip(struct drm_crtc *crtc,
                                struct drm_framebuffer *fb,
                                struct drm_pending_vblank_event *event,
                                uint32_t flags)
{
        struct drm_plane *plane = crtc->primary;
        struct drm_atomic_state *state;
        struct drm_plane_state *plane_state;
        struct drm_crtc_state *crtc_state;
        int ret = 0;

        if (flags & DRM_MODE_PAGE_FLIP_ASYNC)
                return -EINVAL;

        state = drm_atomic_state_alloc(plane->dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
retry:
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                goto fail;
        }
        crtc_state->event = event;

        plane_state = drm_atomic_get_plane_state(state, plane);
        if (IS_ERR(plane_state)) {
                ret = PTR_ERR(plane_state);
                goto fail;
        }

        ret = drm_atomic_set_crtc_for_plane(plane_state, crtc);
        if (ret != 0)
                goto fail;
        drm_atomic_set_fb_for_plane(plane_state, fb);

        /* Make sure we don't accidentally do a full modeset. */
        state->allow_modeset = false;
        if (!crtc_state->active) {
                DRM_DEBUG_ATOMIC("[CRTC:%d] disabled, rejecting legacy flip\n",
                                 crtc->base.id);
                ret = -EINVAL;
                goto fail;
        }

        ret = drm_atomic_nonblocking_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_put(state);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        /*
         * Someone might have exchanged the framebuffer while we dropped locks
         * in the backoff code. We need to fix up the fb refcount tracking the
         * core does for us.
         */
        plane->old_fb = plane->fb;

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_page_flip);

/**
 * drm_atomic_helper_connector_dpms() - connector dpms helper implementation
 * @connector: affected connector
 * @mode: DPMS mode
 *
 * This is the main helper function provided by the atomic helper framework for
 * implementing the legacy DPMS connector interface. It computes the new desired
 * ->active state for the corresponding CRTC (if the connector is enabled) and
 * updates it.
 *
 * Returns:
 * Returns 0 on success, negative errno numbers on failure.
 */
int drm_atomic_helper_connector_dpms(struct drm_connector *connector,
                                     int mode)
{
        struct drm_mode_config *config = &connector->dev->mode_config;
        struct drm_atomic_state *state;
        struct drm_crtc_state *crtc_state;
        struct drm_crtc *crtc;
        struct drm_connector *tmp_connector;
        struct drm_connector_list_iter conn_iter;
        int ret;
        bool active = false;
        int old_mode = connector->dpms;

        if (mode != DRM_MODE_DPMS_ON)
                mode = DRM_MODE_DPMS_OFF;

        connector->dpms = mode;
        crtc = connector->state->crtc;

        if (!crtc)
                return 0;

        state = drm_atomic_state_alloc(connector->dev);
        if (!state)
                return -ENOMEM;

        state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
retry:
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                goto fail;
        }

        WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));

        drm_connector_list_iter_get(connector->dev, &conn_iter);
        drm_for_each_connector_iter(tmp_connector, &conn_iter) {
                if (tmp_connector->state->crtc != crtc)
                        continue;

                if (tmp_connector->dpms == DRM_MODE_DPMS_ON) {
                        active = true;
                        break;
                }
        }
        drm_connector_list_iter_put(&conn_iter);
        crtc_state->active = active;

        ret = drm_atomic_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;
        if (ret != 0)
                connector->dpms = old_mode;
        drm_atomic_state_put(state);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_dpms);

/**
 * drm_atomic_helper_best_encoder - Helper for &drm_connector_helper_funcs
 *                                  ->best_encoder callback
 * @connector: Connector control structure
 *
 * This is a &drm_connector_helper_funcs ->best_encoder callback helper for
 * connectors that support exactly 1 encoder, statically determined at driver
 * init time.
 */
struct drm_encoder *
drm_atomic_helper_best_encoder(struct drm_connector *connector)
{
        WARN_ON(connector->encoder_ids[1]);
        return drm_encoder_find(connector->dev, connector->encoder_ids[0]);
}
EXPORT_SYMBOL(drm_atomic_helper_best_encoder);

/**
 * DOC: atomic state reset and initialization
 *
 * Both the drm core and the atomic helpers assume that there is always the full
 * and correct atomic software state for all connectors, CRTCs and planes
 * available. Which is a bit a problem on driver load and also after system
 * suspend. One way to solve this is to have a hardware state read-out
 * infrastructure which reconstructs the full software state (e.g. the i915
 * driver).
 *
 * The simpler solution is to just reset the software state to everything off,
 * which is easiest to do by calling drm_mode_config_reset(). To facilitate this
 * the atomic helpers provide default reset implementations for all hooks.
 *
 * On the upside the precise state tracking of atomic simplifies system suspend
 * and resume a lot. For drivers using drm_mode_config_reset() a complete recipe
 * is implemented in drm_atomic_helper_suspend() and drm_atomic_helper_resume().
 * For other drivers the building blocks are split out, see the documentation
 * for these functions.
 */

/**
 * drm_atomic_helper_crtc_reset - default ->reset hook for CRTCs
 * @crtc: drm CRTC
 *
 * Resets the atomic state for @crtc by freeing the state pointer (which might
 * be NULL, e.g. at driver load time) and allocating a new empty state object.
 */
void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
{
        if (crtc->state)
                __drm_atomic_helper_crtc_destroy_state(crtc->state);

        kfree(crtc->state);
        crtc->state = kzalloc(sizeof(*crtc->state), GFP_KERNEL);

        if (crtc->state)
                crtc->state->crtc = crtc;
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_reset);

/**
 * __drm_atomic_helper_crtc_duplicate_state - copy atomic CRTC state
 * @crtc: CRTC object
 * @state: atomic CRTC state
 *
 * Copies atomic state from a CRTC's current state and resets inferred values.
 * This is useful for drivers that subclass the CRTC state.
 */
void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
                                              struct drm_crtc_state *state)
{
        memcpy(state, crtc->state, sizeof(*state));

        if (state->mode_blob)
                drm_property_reference_blob(state->mode_blob);
        if (state->degamma_lut)
                drm_property_reference_blob(state->degamma_lut);
        if (state->ctm)
                drm_property_reference_blob(state->ctm);
        if (state->gamma_lut)
                drm_property_reference_blob(state->gamma_lut);
        state->mode_changed = false;
        state->active_changed = false;
        state->planes_changed = false;
        state->connectors_changed = false;
        state->color_mgmt_changed = false;
        state->zpos_changed = false;
        state->event = NULL;
}
EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);

/**
 * drm_atomic_helper_crtc_duplicate_state - default state duplicate hook
 * @crtc: drm CRTC
 *
 * Default CRTC state duplicate hook for drivers which don't have their own
 * subclassed CRTC state structure.
 */
struct drm_crtc_state *
drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc)
{
        struct drm_crtc_state *state;

        if (WARN_ON(!crtc->state))
                return NULL;

        state = kmalloc(sizeof(*state), GFP_KERNEL);
        if (state)
                __drm_atomic_helper_crtc_duplicate_state(crtc, state);

        return state;
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_duplicate_state);

/**
 * __drm_atomic_helper_crtc_destroy_state - release CRTC state
 * @state: CRTC state object to release
 *
 * Releases all resources stored in the CRTC state without actually freeing
 * the memory of the CRTC state. This is useful for drivers that subclass the
 * CRTC state.
 */
void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc_state *state)
{
        drm_property_unreference_blob(state->mode_blob);
        drm_property_unreference_blob(state->degamma_lut);
        drm_property_unreference_blob(state->ctm);
        drm_property_unreference_blob(state->gamma_lut);
}
EXPORT_SYMBOL(__drm_atomic_helper_crtc_destroy_state);

/**
 * drm_atomic_helper_crtc_destroy_state - default state destroy hook
 * @crtc: drm CRTC
 * @state: CRTC state object to release
 *
 * Default CRTC state destroy hook for drivers which don't have their own
 * subclassed CRTC state structure.
 */
void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
                                          struct drm_crtc_state *state)
{
        __drm_atomic_helper_crtc_destroy_state(state);
        kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);

/**
 * drm_atomic_helper_plane_reset - default ->reset hook for planes
 * @plane: drm plane
 *
 * Resets the atomic state for @plane by freeing the state pointer (which might
 * be NULL, e.g. at driver load time) and allocating a new empty state object.
 */
void drm_atomic_helper_plane_reset(struct drm_plane *plane)
{
        if (plane->state)
                __drm_atomic_helper_plane_destroy_state(plane->state);

        kfree(plane->state);
        plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL);

        if (plane->state) {
                plane->state->plane = plane;
                plane->state->rotation = DRM_ROTATE_0;
        }
}
EXPORT_SYMBOL(drm_atomic_helper_plane_reset);

/**
 * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state
 * @plane: plane object
 * @state: atomic plane state
 *
 * Copies atomic state from a plane's current state. This is useful for
 * drivers that subclass the plane state.
 */
void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
                                               struct drm_plane_state *state)
{
        memcpy(state, plane->state, sizeof(*state));

        if (state->fb)
                drm_framebuffer_reference(state->fb);

        state->fence = NULL;
}
EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);

/**
 * drm_atomic_helper_plane_duplicate_state - default state duplicate hook
 * @plane: drm plane
 *
 * Default plane state duplicate hook for drivers which don't have their own
 * subclassed plane state structure.
 */
struct drm_plane_state *
drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane)
{
        struct drm_plane_state *state;

        if (WARN_ON(!plane->state))
                return NULL;

        state = kmalloc(sizeof(*state), GFP_KERNEL);
        if (state)
                __drm_atomic_helper_plane_duplicate_state(plane, state);

        return state;
}
EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);

/**
 * __drm_atomic_helper_plane_destroy_state - release plane state
 * @state: plane state object to release
 *
 * Releases all resources stored in the plane state without actually freeing
 * the memory of the plane state. This is useful for drivers that subclass the
 * plane state.
 */
void __drm_atomic_helper_plane_destroy_state(struct drm_plane_state *state)
{
        if (state->fb)
                drm_framebuffer_unreference(state->fb);

        if (state->fence)
                dma_fence_put(state->fence);
}
EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);

/**
 * drm_atomic_helper_plane_destroy_state - default state destroy hook
 * @plane: drm plane
 * @state: plane state object to release
 *
 * Default plane state destroy hook for drivers which don't have their own
 * subclassed plane state structure.
 */
void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
                                           struct drm_plane_state *state)
{
        __drm_atomic_helper_plane_destroy_state(state);
        kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state);

/**
 * __drm_atomic_helper_connector_reset - reset state on connector
 * @connector: drm connector
 * @conn_state: connector state to assign
 *
 * Initializes the newly allocated @conn_state and assigns it to
 * #connector ->state, usually required when initializing the drivers
 * or when called from the ->reset hook.
 *
 * This is useful for drivers that subclass the connector state.
 */
void
__drm_atomic_helper_connector_reset(struct drm_connector *connector,
                                    struct drm_connector_state *conn_state)
{
        if (conn_state)
                conn_state->connector = connector;

        connector->state = conn_state;
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_reset);

/**
 * drm_atomic_helper_connector_reset - default ->reset hook for connectors
 * @connector: drm connector
 *
 * Resets the atomic state for @connector by freeing the state pointer (which
 * might be NULL, e.g. at driver load time) and allocating a new empty state
 * object.
 */
void drm_atomic_helper_connector_reset(struct drm_connector *connector)
{
        struct drm_connector_state *conn_state =
                kzalloc(sizeof(*conn_state), GFP_KERNEL);

        if (connector->state)
                __drm_atomic_helper_connector_destroy_state(connector->state);

        kfree(connector->state);
        __drm_atomic_helper_connector_reset(connector, conn_state);
}
EXPORT_SYMBOL(drm_atomic_helper_connector_reset);

/**
 * __drm_atomic_helper_connector_duplicate_state - copy atomic connector state
 * @connector: connector object
 * @state: atomic connector state
 *
 * Copies atomic state from a connector's current state. This is useful for
 * drivers that subclass the connector state.
 */
void
__drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
                                            struct drm_connector_state *state)
{
        memcpy(state, connector->state, sizeof(*state));
        if (state->crtc)
                drm_connector_reference(connector);
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);

/**
 * drm_atomic_helper_connector_duplicate_state - default state duplicate hook
 * @connector: drm connector
 *
 * Default connector state duplicate hook for drivers which don't have their own
 * subclassed connector state structure.
 */
struct drm_connector_state *
drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector)
{
        struct drm_connector_state *state;

        if (WARN_ON(!connector->state))
                return NULL;

        state = kmalloc(sizeof(*state), GFP_KERNEL);
        if (state)
                __drm_atomic_helper_connector_duplicate_state(connector, state);

        return state;
}
EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);

/**
 * drm_atomic_helper_duplicate_state - duplicate an atomic state object
 * @dev: DRM device
 * @ctx: lock acquisition context
 *
 * Makes a copy of the current atomic state by looping over all objects and
 * duplicating their respective states. This is used for example by suspend/
 * resume support code to save the state prior to suspend such that it can
 * be restored upon resume.
 *
 * Note that this treats atomic state as persistent between save and restore.
 * Drivers must make sure that this is possible and won't result in confusion
 * or erroneous behaviour.
 *
 * Note that if callers haven't already acquired all modeset locks this might
 * return -EDEADLK, which must be handled by calling drm_modeset_backoff().
 *
 * Returns:
 * A pointer to the copy of the atomic state object on success or an
 * ERR_PTR()-encoded error code on failure.
 *
 * See also:
 * drm_atomic_helper_suspend(), drm_atomic_helper_resume()
 */
struct drm_atomic_state *
drm_atomic_helper_duplicate_state(struct drm_device *dev,
                                  struct drm_modeset_acquire_ctx *ctx)
{
        struct drm_atomic_state *state;
        struct drm_connector *conn;
        struct drm_connector_list_iter conn_iter;
        struct drm_plane *plane;
        struct drm_crtc *crtc;
        int err = 0;

        state = drm_atomic_state_alloc(dev);
        if (!state)
                return ERR_PTR(-ENOMEM);

        state->acquire_ctx = ctx;

        drm_for_each_crtc(crtc, dev) {
                struct drm_crtc_state *crtc_state;

                crtc_state = drm_atomic_get_crtc_state(state, crtc);
                if (IS_ERR(crtc_state)) {
                        err = PTR_ERR(crtc_state);
                        goto free;
                }
        }

        drm_for_each_plane(plane, dev) {
                struct drm_plane_state *plane_state;

                plane_state = drm_atomic_get_plane_state(state, plane);
                if (IS_ERR(plane_state)) {
                        err = PTR_ERR(plane_state);
                        goto free;
                }
        }

        drm_connector_list_iter_get(dev, &conn_iter);
        drm_for_each_connector_iter(conn, &conn_iter) {
                struct drm_connector_state *conn_state;

                conn_state = drm_atomic_get_connector_state(state, conn);
                if (IS_ERR(conn_state)) {
                        err = PTR_ERR(conn_state);
                        drm_connector_list_iter_put(&conn_iter);
                        goto free;
                }
        }
        drm_connector_list_iter_put(&conn_iter);

        /* clear the acquire context so that it isn't accidentally reused */
        state->acquire_ctx = NULL;

free:
        if (err < 0) {
                drm_atomic_state_put(state);
                state = ERR_PTR(err);
        }

        return state;
}
EXPORT_SYMBOL(drm_atomic_helper_duplicate_state);

/**
 * __drm_atomic_helper_connector_destroy_state - release connector state
 * @state: connector state object to release
 *
 * Releases all resources stored in the connector state without actually
 * freeing the memory of the connector state. This is useful for drivers that
 * subclass the connector state.
 */
void
__drm_atomic_helper_connector_destroy_state(struct drm_connector_state *state)
{
        if (state->crtc)
                drm_connector_unreference(state->connector);
}
EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state);

/**
 * drm_atomic_helper_connector_destroy_state - default state destroy hook
 * @connector: drm connector
 * @state: connector state object to release
 *
 * Default connector state destroy hook for drivers which don't have their own
 * subclassed connector state structure.
 */
void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
                                          struct drm_connector_state *state)
{
        __drm_atomic_helper_connector_destroy_state(state);
        kfree(state);
}
EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);

/**
 * drm_atomic_helper_legacy_gamma_set - set the legacy gamma correction table
 * @crtc: CRTC object
 * @red: red correction table
 * @green: green correction table
 * @blue: green correction table
 * @size: size of the tables
 *
 * Implements support for legacy gamma correction table for drivers
 * that support color management through the DEGAMMA_LUT/GAMMA_LUT
 * properties.
 */
int drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
                                       u16 *red, u16 *green, u16 *blue,
                                       uint32_t size)
{
        struct drm_device *dev = crtc->dev;
        struct drm_mode_config *config = &dev->mode_config;
        struct drm_atomic_state *state;
        struct drm_crtc_state *crtc_state;
        struct drm_property_blob *blob = NULL;
        struct drm_color_lut *blob_data;
        int i, ret = 0;

        state = drm_atomic_state_alloc(crtc->dev);
        if (!state)
                return -ENOMEM;

        blob = drm_property_create_blob(dev,
                                        sizeof(struct drm_color_lut) * size,
                                        NULL);
        if (IS_ERR(blob)) {
                ret = PTR_ERR(blob);
                blob = NULL;
                goto fail;
        }

        /* Prepare GAMMA_LUT with the legacy values. */
        blob_data = (struct drm_color_lut *) blob->data;
        for (i = 0; i < size; i++) {
                blob_data[i].red = red[i];
                blob_data[i].green = green[i];
                blob_data[i].blue = blue[i];
        }

        state->acquire_ctx = crtc->dev->mode_config.acquire_ctx;
retry:
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state)) {
                ret = PTR_ERR(crtc_state);
                goto fail;
        }

        /* Reset DEGAMMA_LUT and CTM properties. */
        ret = drm_atomic_crtc_set_property(crtc, crtc_state,
                        config->degamma_lut_property, 0);
        if (ret)
                goto fail;

        ret = drm_atomic_crtc_set_property(crtc, crtc_state,
                        config->ctm_property, 0);
        if (ret)
                goto fail;

        ret = drm_atomic_crtc_set_property(crtc, crtc_state,
                        config->gamma_lut_property, blob->base.id);
        if (ret)
                goto fail;

        ret = drm_atomic_commit(state);
fail:
        if (ret == -EDEADLK)
                goto backoff;

        drm_atomic_state_put(state);
        drm_property_unreference_blob(blob);
        return ret;

backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);

        goto retry;
}
EXPORT_SYMBOL(drm_atomic_helper_legacy_gamma_set);