drivers/gpu/drm/drm_atomic_state_helper.c

   1 /*
   2  * Copyright (C) 2018 Intel Corp.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20  * OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  * Authors:
  23  * Rob Clark <robdclark@gmail.com>
  24  * Daniel Vetter <daniel.vetter@ffwll.ch>
  25  */
  26
  27 #include <drm/drm_atomic.h>
  28 #include <drm/drm_atomic_state_helper.h>
  29 #include <drm/drm_bridge.h>
  30 #include <drm/drm_connector.h>
  31 #include <drm/drm_crtc.h>
  32 #include <drm/drm_device.h>
  33 #include <drm/drm_plane.h>
  34 #include <drm/drm_print.h>
  35 #include <drm/drm_vblank.h>
  36 #include <drm/drm_writeback.h>
  37
  38 #include <linux/slab.h>
  39 #include <linux/dma-fence.h>
  40
  41 /**
  42  * DOC: atomic state reset and initialization
  43  *
  44  * Both the drm core and the atomic helpers assume that there is always the full
  45  * and correct atomic software state for all connectors, CRTCs and planes
  46  * available. Which is a bit a problem on driver load and also after system
  47  * suspend. One way to solve this is to have a hardware state read-out
  48  * infrastructure which reconstructs the full software state (e.g. the i915
  49  * driver).
  50  *
  51  * The simpler solution is to just reset the software state to everything off,
  52  * which is easiest to do by calling drm_mode_config_reset(). To facilitate this
  53  * the atomic helpers provide default reset implementations for all hooks.
  54  *
  55  * On the upside the precise state tracking of atomic simplifies system suspend
  56  * and resume a lot. For drivers using drm_mode_config_reset() a complete recipe
  57  * is implemented in drm_atomic_helper_suspend() and drm_atomic_helper_resume().
  58  * For other drivers the building blocks are split out, see the documentation
  59  * for these functions.
  60  */
  61
  62 /**
  63  * __drm_atomic_helper_crtc_state_reset - reset the CRTC state
  64  * @crtc_state: atomic CRTC state, must not be NULL
  65  * @crtc: CRTC object, must not be NULL
  66  *
  67  * Initializes the newly allocated @crtc_state with default
  68  * values. This is useful for drivers that subclass the CRTC state.
  69  */
  70 void
  71 __drm_atomic_helper_crtc_state_reset(struct drm_crtc_state *crtc_state,
  72                                      struct drm_crtc *crtc)
  73 {
  74         crtc_state->crtc = crtc;
  75 }
  76 EXPORT_SYMBOL(__drm_atomic_helper_crtc_state_reset);
  77
  78 /**
  79  * __drm_atomic_helper_crtc_reset - reset state on CRTC
  80  * @crtc: drm CRTC
  81  * @crtc_state: CRTC state to assign
  82  *
  83  * Initializes the newly allocated @crtc_state and assigns it to
  84  * the &drm_crtc->state pointer of @crtc, usually required when
  85  * initializing the drivers or when called from the &drm_crtc_funcs.reset
  86  * hook.
  87  *
  88  * This is useful for drivers that subclass the CRTC state.
  89  */
  90 void
  91 __drm_atomic_helper_crtc_reset(struct drm_crtc *crtc,
  92                                struct drm_crtc_state *crtc_state)
  93 {
  94         if (crtc_state)
  95                 __drm_atomic_helper_crtc_state_reset(crtc_state, crtc);
  96
  97         if (drm_dev_has_vblank(crtc->dev))
  98                 drm_crtc_vblank_reset(crtc);
  99
 100         crtc->state = crtc_state;
 101 }
 102 EXPORT_SYMBOL(__drm_atomic_helper_crtc_reset);
 103
 104 /**
 105  * drm_atomic_helper_crtc_reset - default &drm_crtc_funcs.reset hook for CRTCs
 106  * @crtc: drm CRTC
 107  *
 108  * Resets the atomic state for @crtc by freeing the state pointer (which might
 109  * be NULL, e.g. at driver load time) and allocating a new empty state object.
 110  */
 111 void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
 112 {
 113         struct drm_crtc_state *crtc_state =
 114                 kzalloc(sizeof(*crtc->state), GFP_KERNEL);
 115
 116         if (crtc->state)
 117                 crtc->funcs->atomic_destroy_state(crtc, crtc->state);
 118
 119         __drm_atomic_helper_crtc_reset(crtc, crtc_state);
 120 }
 121 EXPORT_SYMBOL(drm_atomic_helper_crtc_reset);
 122
 123 /**
 124  * __drm_atomic_helper_crtc_duplicate_state - copy atomic CRTC state
 125  * @crtc: CRTC object
 126  * @state: atomic CRTC state
 127  *
 128  * Copies atomic state from a CRTC's current state and resets inferred values.
 129  * This is useful for drivers that subclass the CRTC state.
 130  */
 131 void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
 132                                               struct drm_crtc_state *state)
 133 {
 134         memcpy(state, crtc->state, sizeof(*state));
 135
 136         if (state->mode_blob)
 137                 drm_property_blob_get(state->mode_blob);
 138         if (state->degamma_lut)
 139                 drm_property_blob_get(state->degamma_lut);
 140         if (state->ctm)
 141                 drm_property_blob_get(state->ctm);
 142         if (state->gamma_lut)
 143                 drm_property_blob_get(state->gamma_lut);
 144         state->mode_changed = false;
 145         state->active_changed = false;
 146         state->planes_changed = false;
 147         state->connectors_changed = false;
 148         state->color_mgmt_changed = false;
 149         state->zpos_changed = false;
 150         state->commit = NULL;
 151         state->event = NULL;
 152         state->async_flip = false;
 153
 154         /* Self refresh should be canceled when a new update is available */
 155         state->active = drm_atomic_crtc_effectively_active(state);
 156         state->self_refresh_active = false;
 157 }
 158 EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);
 159
 160 /**
 161  * drm_atomic_helper_crtc_duplicate_state - default state duplicate hook
 162  * @crtc: drm CRTC
 163  *
 164  * Default CRTC state duplicate hook for drivers which don't have their own
 165  * subclassed CRTC state structure.
 166  */
 167 struct drm_crtc_state *
 168 drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc)
 169 {
 170         struct drm_crtc_state *state;
 171
 172         if (WARN_ON(!crtc->state))
 173                 return NULL;
 174
 175         state = kmalloc(sizeof(*state), GFP_KERNEL);
 176         if (state)
 177                 __drm_atomic_helper_crtc_duplicate_state(crtc, state);
 178
 179         return state;
 180 }
 181 EXPORT_SYMBOL(drm_atomic_helper_crtc_duplicate_state);
 182
 183 /**
 184  * __drm_atomic_helper_crtc_destroy_state - release CRTC state
 185  * @state: CRTC state object to release
 186  *
 187  * Releases all resources stored in the CRTC state without actually freeing
 188  * the memory of the CRTC state. This is useful for drivers that subclass the
 189  * CRTC state.
 190  */
 191 void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc_state *state)
 192 {
 193         if (state->commit) {
 194                 /*
 195                  * In the event that a non-blocking commit returns
 196                  * -ERESTARTSYS before the commit_tail work is queued, we will
 197                  * have an extra reference to the commit object. Release it, if
 198                  * the event has not been consumed by the worker.
 199                  *
 200                  * state->event may be freed, so we can't directly look at
 201                  * state->event->base.completion.
 202                  */
 203                 if (state->event && state->commit->abort_completion)
 204                         drm_crtc_commit_put(state->commit);
 205
 206                 kfree(state->commit->event);
 207                 state->commit->event = NULL;
 208
 209                 drm_crtc_commit_put(state->commit);
 210         }
 211
 212         drm_property_blob_put(state->mode_blob);
 213         drm_property_blob_put(state->degamma_lut);
 214         drm_property_blob_put(state->ctm);
 215         drm_property_blob_put(state->gamma_lut);
 216 }
 217 EXPORT_SYMBOL(__drm_atomic_helper_crtc_destroy_state);
 218
 219 /**
 220  * drm_atomic_helper_crtc_destroy_state - default state destroy hook
 221  * @crtc: drm CRTC
 222  * @state: CRTC state object to release
 223  *
 224  * Default CRTC state destroy hook for drivers which don't have their own
 225  * subclassed CRTC state structure.
 226  */
 227 void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
 228                                           struct drm_crtc_state *state)
 229 {
 230         __drm_atomic_helper_crtc_destroy_state(state);
 231         kfree(state);
 232 }
 233 EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);
 234
 235 /**
 236  * __drm_atomic_helper_plane_state_reset - resets plane state to default values
 237  * @plane_state: atomic plane state, must not be NULL
 238  * @plane: plane object, must not be NULL
 239  *
 240  * Initializes the newly allocated @plane_state with default
 241  * values. This is useful for drivers that subclass the CRTC state.
 242  */
 243 void __drm_atomic_helper_plane_state_reset(struct drm_plane_state *plane_state,
 244                                            struct drm_plane *plane)
 245 {
 246         plane_state->plane = plane;
 247         plane_state->rotation = DRM_MODE_ROTATE_0;
 248
 249         plane_state->alpha = DRM_BLEND_ALPHA_OPAQUE;
 250         plane_state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
 251 }
 252 EXPORT_SYMBOL(__drm_atomic_helper_plane_state_reset);
 253
 254 /**
 255  * __drm_atomic_helper_plane_reset - reset state on plane
 256  * @plane: drm plane
 257  * @plane_state: plane state to assign
 258  *
 259  * Initializes the newly allocated @plane_state and assigns it to
 260  * the &drm_crtc->state pointer of @plane, usually required when
 261  * initializing the drivers or when called from the &drm_plane_funcs.reset
 262  * hook.
 263  *
 264  * This is useful for drivers that subclass the plane state.
 265  */
 266 void __drm_atomic_helper_plane_reset(struct drm_plane *plane,
 267                                      struct drm_plane_state *plane_state)
 268 {
 269         if (plane_state)
 270                 __drm_atomic_helper_plane_state_reset(plane_state, plane);
 271
 272         plane->state = plane_state;
 273 }
 274 EXPORT_SYMBOL(__drm_atomic_helper_plane_reset);
 275
 276 /**
 277  * drm_atomic_helper_plane_reset - default &drm_plane_funcs.reset hook for planes
 278  * @plane: drm plane
 279  *
 280  * Resets the atomic state for @plane by freeing the state pointer (which might
 281  * be NULL, e.g. at driver load time) and allocating a new empty state object.
 282  */
 283 void drm_atomic_helper_plane_reset(struct drm_plane *plane)
 284 {
 285         if (plane->state)
 286                 __drm_atomic_helper_plane_destroy_state(plane->state);
 287
 288         kfree(plane->state);
 289         plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL);
 290         if (plane->state)
 291                 __drm_atomic_helper_plane_reset(plane, plane->state);
 292 }
 293 EXPORT_SYMBOL(drm_atomic_helper_plane_reset);
 294
 295 /**
 296  * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state
 297  * @plane: plane object
 298  * @state: atomic plane state
 299  *
 300  * Copies atomic state from a plane's current state. This is useful for
 301  * drivers that subclass the plane state.
 302  */
 303 void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
 304                                                struct drm_plane_state *state)
 305 {
 306         memcpy(state, plane->state, sizeof(*state));
 307
 308         if (state->fb)
 309                 drm_framebuffer_get(state->fb);
 310
 311         state->fence = NULL;
 312         state->commit = NULL;
 313         state->fb_damage_clips = NULL;
 314 }
 315 EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);
 316
 317 /**
 318  * drm_atomic_helper_plane_duplicate_state - default state duplicate hook
 319  * @plane: drm plane
 320  *
 321  * Default plane state duplicate hook for drivers which don't have their own
 322  * subclassed plane state structure.
 323  */
 324 struct drm_plane_state *
 325 drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane)
 326 {
 327         struct drm_plane_state *state;
 328
 329         if (WARN_ON(!plane->state))
 330                 return NULL;
 331
 332         state = kmalloc(sizeof(*state), GFP_KERNEL);
 333         if (state)
 334                 __drm_atomic_helper_plane_duplicate_state(plane, state);
 335
 336         return state;
 337 }
 338 EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);
 339
 340 /**
 341  * __drm_atomic_helper_plane_destroy_state - release plane state
 342  * @state: plane state object to release
 343  *
 344  * Releases all resources stored in the plane state without actually freeing
 345  * the memory of the plane state. This is useful for drivers that subclass the
 346  * plane state.
 347  */
 348 void __drm_atomic_helper_plane_destroy_state(struct drm_plane_state *state)
 349 {
 350         if (state->fb)
 351                 drm_framebuffer_put(state->fb);
 352
 353         if (state->fence)
 354                 dma_fence_put(state->fence);
 355
 356         if (state->commit)
 357                 drm_crtc_commit_put(state->commit);
 358
 359         drm_property_blob_put(state->fb_damage_clips);
 360 }
 361 EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);
 362
 363 /**
 364  * drm_atomic_helper_plane_destroy_state - default state destroy hook
 365  * @plane: drm plane
 366  * @state: plane state object to release
 367  *
 368  * Default plane state destroy hook for drivers which don't have their own
 369  * subclassed plane state structure.
 370  */
 371 void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
 372                                            struct drm_plane_state *state)
 373 {
 374         __drm_atomic_helper_plane_destroy_state(state);
 375         kfree(state);
 376 }
 377 EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state);
 378
 379 /**
 380  * __drm_atomic_helper_connector_state_reset - reset the connector state
 381  * @conn_state: atomic connector state, must not be NULL
 382  * @connector: connectotr object, must not be NULL
 383  *
 384  * Initializes the newly allocated @conn_state with default
 385  * values. This is useful for drivers that subclass the connector state.
 386  */
 387 void
 388 __drm_atomic_helper_connector_state_reset(struct drm_connector_state *conn_state,
 389                                           struct drm_connector *connector)
 390 {
 391         conn_state->connector = connector;
 392 }
 393 EXPORT_SYMBOL(__drm_atomic_helper_connector_state_reset);
 394
 395 /**
 396  * __drm_atomic_helper_connector_reset - reset state on connector
 397  * @connector: drm connector
 398  * @conn_state: connector state to assign
 399  *
 400  * Initializes the newly allocated @conn_state and assigns it to
 401  * the &drm_connector->state pointer of @connector, usually required when
 402  * initializing the drivers or when called from the &drm_connector_funcs.reset
 403  * hook.
 404  *
 405  * This is useful for drivers that subclass the connector state.
 406  */
 407 void
 408 __drm_atomic_helper_connector_reset(struct drm_connector *connector,
 409                                     struct drm_connector_state *conn_state)
 410 {
 411         if (conn_state)
 412                 __drm_atomic_helper_connector_state_reset(conn_state, connector);
 413
 414         connector->state = conn_state;
 415 }
 416 EXPORT_SYMBOL(__drm_atomic_helper_connector_reset);
 417
 418 /**
 419  * drm_atomic_helper_connector_reset - default &drm_connector_funcs.reset hook for connectors
 420  * @connector: drm connector
 421  *
 422  * Resets the atomic state for @connector by freeing the state pointer (which
 423  * might be NULL, e.g. at driver load time) and allocating a new empty state
 424  * object.
 425  */
 426 void drm_atomic_helper_connector_reset(struct drm_connector *connector)
 427 {
 428         struct drm_connector_state *conn_state =
 429                 kzalloc(sizeof(*conn_state), GFP_KERNEL);
 430
 431         if (connector->state)
 432                 __drm_atomic_helper_connector_destroy_state(connector->state);
 433
 434         kfree(connector->state);
 435         __drm_atomic_helper_connector_reset(connector, conn_state);
 436 }
 437 EXPORT_SYMBOL(drm_atomic_helper_connector_reset);
 438
 439 /**
 440  * drm_atomic_helper_connector_tv_reset - Resets TV connector properties
 441  * @connector: DRM connector
 442  *
 443  * Resets the TV-related properties attached to a connector.
 444  */
 445 void drm_atomic_helper_connector_tv_reset(struct drm_connector *connector)
 446 {
 447         struct drm_cmdline_mode *cmdline = &connector->cmdline_mode;
 448         struct drm_connector_state *state = connector->state;
 449
 450         state->tv.margins.left = cmdline->tv_margins.left;
 451         state->tv.margins.right = cmdline->tv_margins.right;
 452         state->tv.margins.top = cmdline->tv_margins.top;
 453         state->tv.margins.bottom = cmdline->tv_margins.bottom;
 454 }
 455 EXPORT_SYMBOL(drm_atomic_helper_connector_tv_reset);
 456
 457 /**
 458  * __drm_atomic_helper_connector_duplicate_state - copy atomic connector state
 459  * @connector: connector object
 460  * @state: atomic connector state
 461  *
 462  * Copies atomic state from a connector's current state. This is useful for
 463  * drivers that subclass the connector state.
 464  */
 465 void
 466 __drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
 467                                             struct drm_connector_state *state)
 468 {
 469         memcpy(state, connector->state, sizeof(*state));
 470         if (state->crtc)
 471                 drm_connector_get(connector);
 472         state->commit = NULL;
 473
 474         if (state->hdr_output_metadata)
 475                 drm_property_blob_get(state->hdr_output_metadata);
 476
 477         /* Don't copy over a writeback job, they are used only once */
 478         state->writeback_job = NULL;
 479 }
 480 EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);
 481
 482 /**
 483  * drm_atomic_helper_connector_duplicate_state - default state duplicate hook
 484  * @connector: drm connector
 485  *
 486  * Default connector state duplicate hook for drivers which don't have their own
 487  * subclassed connector state structure.
 488  */
 489 struct drm_connector_state *
 490 drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector)
 491 {
 492         struct drm_connector_state *state;
 493
 494         if (WARN_ON(!connector->state))
 495                 return NULL;
 496
 497         state = kmalloc(sizeof(*state), GFP_KERNEL);
 498         if (state)
 499                 __drm_atomic_helper_connector_duplicate_state(connector, state);
 500
 501         return state;
 502 }
 503 EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);
 504
 505 /**
 506  * __drm_atomic_helper_connector_destroy_state - release connector state
 507  * @state: connector state object to release
 508  *
 509  * Releases all resources stored in the connector state without actually
 510  * freeing the memory of the connector state. This is useful for drivers that
 511  * subclass the connector state.
 512  */
 513 void
 514 __drm_atomic_helper_connector_destroy_state(struct drm_connector_state *state)
 515 {
 516         if (state->crtc)
 517                 drm_connector_put(state->connector);
 518
 519         if (state->commit)
 520                 drm_crtc_commit_put(state->commit);
 521
 522         if (state->writeback_job)
 523                 drm_writeback_cleanup_job(state->writeback_job);
 524
 525         drm_property_blob_put(state->hdr_output_metadata);
 526 }
 527 EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state);
 528
 529 /**
 530  * drm_atomic_helper_connector_destroy_state - default state destroy hook
 531  * @connector: drm connector
 532  * @state: connector state object to release
 533  *
 534  * Default connector state destroy hook for drivers which don't have their own
 535  * subclassed connector state structure.
 536  */
 537 void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
 538                                           struct drm_connector_state *state)
 539 {
 540         __drm_atomic_helper_connector_destroy_state(state);
 541         kfree(state);
 542 }
 543 EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);
 544
 545 /**
 546  * __drm_atomic_helper_private_obj_duplicate_state - copy atomic private state
 547  * @obj: CRTC object
 548  * @state: new private object state
 549  *
 550  * Copies atomic state from a private objects's current state and resets inferred values.
 551  * This is useful for drivers that subclass the private state.
 552  */
 553 void __drm_atomic_helper_private_obj_duplicate_state(struct drm_private_obj *obj,
 554                                                      struct drm_private_state *state)
 555 {
 556         memcpy(state, obj->state, sizeof(*state));
 557 }
 558 EXPORT_SYMBOL(__drm_atomic_helper_private_obj_duplicate_state);
 559
 560 /**
 561  * __drm_atomic_helper_bridge_duplicate_state() - Copy atomic bridge state
 562  * @bridge: bridge object
 563  * @state: atomic bridge state
 564  *
 565  * Copies atomic state from a bridge's current state and resets inferred values.
 566  * This is useful for drivers that subclass the bridge state.
 567  */
 568 void __drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge,
 569                                                 struct drm_bridge_state *state)
 570 {
 571         __drm_atomic_helper_private_obj_duplicate_state(&bridge->base,
 572                                                         &state->base);
 573         state->bridge = bridge;
 574 }
 575 EXPORT_SYMBOL(__drm_atomic_helper_bridge_duplicate_state);
 576
 577 /**
 578  * drm_atomic_helper_bridge_duplicate_state() - Duplicate a bridge state object
 579  * @bridge: bridge object
 580  *
 581  * Allocates a new bridge state and initializes it with the current bridge
 582  * state values. This helper is meant to be used as a bridge
 583  * &drm_bridge_funcs.atomic_duplicate_state hook for bridges that don't
 584  * subclass the bridge state.
 585  */
 586 struct drm_bridge_state *
 587 drm_atomic_helper_bridge_duplicate_state(struct drm_bridge *bridge)
 588 {
 589         struct drm_bridge_state *new;
 590
 591         if (WARN_ON(!bridge->base.state))
 592                 return NULL;
 593
 594         new = kzalloc(sizeof(*new), GFP_KERNEL);
 595         if (new)
 596                 __drm_atomic_helper_bridge_duplicate_state(bridge, new);
 597
 598         return new;
 599 }
 600 EXPORT_SYMBOL(drm_atomic_helper_bridge_duplicate_state);
 601
 602 /**
 603  * drm_atomic_helper_bridge_destroy_state() - Destroy a bridge state object
 604  * @bridge: the bridge this state refers to
 605  * @state: bridge state to destroy
 606  *
 607  * Destroys a bridge state previously created by
 608  * &drm_atomic_helper_bridge_reset() or
 609  * &drm_atomic_helper_bridge_duplicate_state(). This helper is meant to be
 610  * used as a bridge &drm_bridge_funcs.atomic_destroy_state hook for bridges
 611  * that don't subclass the bridge state.
 612  */
 613 void drm_atomic_helper_bridge_destroy_state(struct drm_bridge *bridge,
 614                                             struct drm_bridge_state *state)
 615 {
 616         kfree(state);
 617 }
 618 EXPORT_SYMBOL(drm_atomic_helper_bridge_destroy_state);
 619
 620 /**
 621  * __drm_atomic_helper_bridge_reset() - Initialize a bridge state to its
 622  *                                      default
 623  * @bridge: the bridge this state refers to
 624  * @state: bridge state to initialize
 625  *
 626  * Initializes the bridge state to default values. This is meant to be called
 627  * by the bridge &drm_bridge_funcs.atomic_reset hook for bridges that subclass
 628  * the bridge state.
 629  */
 630 void __drm_atomic_helper_bridge_reset(struct drm_bridge *bridge,
 631                                       struct drm_bridge_state *state)
 632 {
 633         memset(state, 0, sizeof(*state));
 634         state->bridge = bridge;
 635 }
 636 EXPORT_SYMBOL(__drm_atomic_helper_bridge_reset);
 637
 638 /**
 639  * drm_atomic_helper_bridge_reset() - Allocate and initialize a bridge state
 640  *                                    to its default
 641  * @bridge: the bridge this state refers to
 642  *
 643  * Allocates the bridge state and initializes it to default values. This helper
 644  * is meant to be used as a bridge &drm_bridge_funcs.atomic_reset hook for
 645  * bridges that don't subclass the bridge state.
 646  */
 647 struct drm_bridge_state *
 648 drm_atomic_helper_bridge_reset(struct drm_bridge *bridge)
 649 {
 650         struct drm_bridge_state *bridge_state;
 651
 652         bridge_state = kzalloc(sizeof(*bridge_state), GFP_KERNEL);
 653         if (!bridge_state)
 654                 return ERR_PTR(-ENOMEM);
 655
 656         __drm_atomic_helper_bridge_reset(bridge, bridge_state);
 657         return bridge_state;
 658 }
 659 EXPORT_SYMBOL(drm_atomic_helper_bridge_reset);