1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * drm gem framebuffer helper functions
5 * Copyright (C) 2017 Noralf Trønnes
8 #include <linux/dma-buf.h>
9 #include <linux/dma-fence.h>
10 #include <linux/reservation.h>
11 #include <linux/slab.h>
14 #include <drm/drm_atomic.h>
15 #include <drm/drm_atomic_uapi.h>
16 #include <drm/drm_damage_helper.h>
17 #include <drm/drm_fb_helper.h>
18 #include <drm/drm_fourcc.h>
19 #include <drm/drm_framebuffer.h>
20 #include <drm/drm_gem.h>
21 #include <drm/drm_gem_framebuffer_helper.h>
22 #include <drm/drm_modeset_helper.h>
23 #include <drm/drm_simple_kms_helper.h>
28 * This library provides helpers for drivers that don't subclass
29 * &drm_framebuffer and use &drm_gem_object for their backing storage.
31 * Drivers without additional needs to validate framebuffers can simply use
32 * drm_gem_fb_create() and everything is wired up automatically. Other drivers
33 * can use all parts independently.
37 * drm_gem_fb_get_obj() - Get GEM object backing the framebuffer
41 * No additional reference is taken beyond the one that the &drm_frambuffer
45 * Pointer to &drm_gem_object for the given framebuffer and plane index or NULL
46 * if it does not exist.
48 struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
54 return fb->obj[plane];
56 EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj);
58 static struct drm_framebuffer *
59 drm_gem_fb_alloc(struct drm_device *dev,
60 const struct drm_mode_fb_cmd2 *mode_cmd,
61 struct drm_gem_object **obj, unsigned int num_planes,
62 const struct drm_framebuffer_funcs *funcs)
64 struct drm_framebuffer *fb;
67 fb = kzalloc(sizeof(*fb), GFP_KERNEL);
69 return ERR_PTR(-ENOMEM);
71 drm_helper_mode_fill_fb_struct(dev, fb, mode_cmd);
73 for (i = 0; i < num_planes; i++)
76 ret = drm_framebuffer_init(dev, fb, funcs);
78 DRM_DEV_ERROR(dev->dev, "Failed to init framebuffer: %d\n",
88 * drm_gem_fb_destroy - Free GEM backed framebuffer
91 * Frees a GEM backed framebuffer with its backing buffer(s) and the structure
92 * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy
95 void drm_gem_fb_destroy(struct drm_framebuffer *fb)
99 for (i = 0; i < 4; i++)
100 drm_gem_object_put_unlocked(fb->obj[i]);
102 drm_framebuffer_cleanup(fb);
105 EXPORT_SYMBOL(drm_gem_fb_destroy);
108 * drm_gem_fb_create_handle - Create handle for GEM backed framebuffer
110 * @file: DRM file to register the handle for
111 * @handle: Pointer to return the created handle
113 * This function creates a handle for the GEM object backing the framebuffer.
114 * Drivers can use this as their &drm_framebuffer_funcs->create_handle
115 * callback. The GETFB IOCTL calls into this callback.
118 * 0 on success or a negative error code on failure.
120 int drm_gem_fb_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
121 unsigned int *handle)
123 return drm_gem_handle_create(file, fb->obj[0], handle);
125 EXPORT_SYMBOL(drm_gem_fb_create_handle);
128 * drm_gem_fb_create_with_funcs() - Helper function for the
129 * &drm_mode_config_funcs.fb_create
132 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
133 * @mode_cmd: Metadata from the userspace framebuffer creation request
134 * @funcs: vtable to be used for the new framebuffer object
136 * This function can be used to set &drm_framebuffer_funcs for drivers that need
137 * custom framebuffer callbacks. Use drm_gem_fb_create() if you don't need to
138 * change &drm_framebuffer_funcs. The function does buffer size validation.
141 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
143 struct drm_framebuffer *
144 drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file,
145 const struct drm_mode_fb_cmd2 *mode_cmd,
146 const struct drm_framebuffer_funcs *funcs)
148 const struct drm_format_info *info;
149 struct drm_gem_object *objs[4];
150 struct drm_framebuffer *fb;
153 info = drm_get_format_info(dev, mode_cmd);
155 return ERR_PTR(-EINVAL);
157 for (i = 0; i < info->num_planes; i++) {
158 unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
159 unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
160 unsigned int min_size;
162 objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]);
164 DRM_DEBUG_KMS("Failed to lookup GEM object\n");
166 goto err_gem_object_put;
169 min_size = (height - 1) * mode_cmd->pitches[i]
170 + drm_format_info_min_pitch(info, i, width)
171 + mode_cmd->offsets[i];
173 if (objs[i]->size < min_size) {
174 drm_gem_object_put_unlocked(objs[i]);
176 goto err_gem_object_put;
180 fb = drm_gem_fb_alloc(dev, mode_cmd, objs, i, funcs);
183 goto err_gem_object_put;
189 for (i--; i >= 0; i--)
190 drm_gem_object_put_unlocked(objs[i]);
194 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs);
196 static const struct drm_framebuffer_funcs drm_gem_fb_funcs = {
197 .destroy = drm_gem_fb_destroy,
198 .create_handle = drm_gem_fb_create_handle,
202 * drm_gem_fb_create() - Helper function for the
203 * &drm_mode_config_funcs.fb_create callback
205 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
206 * @mode_cmd: Metadata from the userspace framebuffer creation request
208 * This function creates a new framebuffer object described by
209 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
210 * backing the framebuffer.
212 * If your hardware has special alignment or pitch requirements these should be
213 * checked before calling this function. The function does buffer size
214 * validation. Use drm_gem_fb_create_with_dirty() if you need framebuffer
217 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
218 * The ADDFB2 IOCTL calls into this callback.
221 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
223 struct drm_framebuffer *
224 drm_gem_fb_create(struct drm_device *dev, struct drm_file *file,
225 const struct drm_mode_fb_cmd2 *mode_cmd)
227 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
230 EXPORT_SYMBOL_GPL(drm_gem_fb_create);
232 static const struct drm_framebuffer_funcs drm_gem_fb_funcs_dirtyfb = {
233 .destroy = drm_gem_fb_destroy,
234 .create_handle = drm_gem_fb_create_handle,
235 .dirty = drm_atomic_helper_dirtyfb,
239 * drm_gem_fb_create_with_dirty() - Helper function for the
240 * &drm_mode_config_funcs.fb_create callback
242 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
243 * @mode_cmd: Metadata from the userspace framebuffer creation request
245 * This function creates a new framebuffer object described by
246 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
247 * backing the framebuffer. drm_atomic_helper_dirtyfb() is used for the dirty
248 * callback giving framebuffer flushing through the atomic machinery. Use
249 * drm_gem_fb_create() if you don't need the dirty callback.
250 * The function does buffer size validation.
252 * Drivers should also call drm_plane_enable_fb_damage_clips() on all planes
253 * to enable userspace to use damage clips also with the ATOMIC IOCTL.
255 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
256 * The ADDFB2 IOCTL calls into this callback.
259 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
261 struct drm_framebuffer *
262 drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
263 const struct drm_mode_fb_cmd2 *mode_cmd)
265 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
266 &drm_gem_fb_funcs_dirtyfb);
268 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_dirty);
271 * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer
273 * @state: Plane state the fence will be attached to
275 * This function prepares a GEM backed framebuffer for scanout by checking if
276 * the plane framebuffer has a DMA-BUF attached. If it does, it extracts the
277 * exclusive fence and attaches it to the plane state for the atomic helper to
278 * wait on. This function can be used as the &drm_plane_helper_funcs.prepare_fb
281 * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
282 * gem based framebuffer drivers which have their buffers always pinned in
285 int drm_gem_fb_prepare_fb(struct drm_plane *plane,
286 struct drm_plane_state *state)
288 struct dma_buf *dma_buf;
289 struct dma_fence *fence;
294 dma_buf = drm_gem_fb_get_obj(state->fb, 0)->dma_buf;
296 fence = reservation_object_get_excl_rcu(dma_buf->resv);
297 drm_atomic_set_fence_for_plane(state, fence);
302 EXPORT_SYMBOL_GPL(drm_gem_fb_prepare_fb);
305 * drm_gem_fb_simple_display_pipe_prepare_fb - prepare_fb helper for
306 * &drm_simple_display_pipe
307 * @pipe: Simple display pipe
308 * @plane_state: Plane state
310 * This function uses drm_gem_fb_prepare_fb() to check if the plane FB has a
311 * &dma_buf attached, extracts the exclusive fence and attaches it to plane
312 * state for the atomic helper to wait on. Drivers can use this as their
313 * &drm_simple_display_pipe_funcs.prepare_fb callback.
315 int drm_gem_fb_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
316 struct drm_plane_state *plane_state)
318 return drm_gem_fb_prepare_fb(&pipe->plane, plane_state);
320 EXPORT_SYMBOL(drm_gem_fb_simple_display_pipe_prepare_fb);
323 * drm_gem_fbdev_fb_create - Create a GEM backed &drm_framebuffer for fbdev
326 * @sizes: fbdev size description
327 * @pitch_align: Optional pitch alignment
328 * @obj: GEM object backing the framebuffer
329 * @funcs: Optional vtable to be used for the new framebuffer object when the
330 * dirty callback is needed.
332 * This function creates a framebuffer from a &drm_fb_helper_surface_size
333 * description for use in the &drm_fb_helper_funcs.fb_probe callback.
336 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
338 struct drm_framebuffer *
339 drm_gem_fbdev_fb_create(struct drm_device *dev,
340 struct drm_fb_helper_surface_size *sizes,
341 unsigned int pitch_align, struct drm_gem_object *obj,
342 const struct drm_framebuffer_funcs *funcs)
344 struct drm_mode_fb_cmd2 mode_cmd = { 0 };
346 mode_cmd.width = sizes->surface_width;
347 mode_cmd.height = sizes->surface_height;
348 mode_cmd.pitches[0] = sizes->surface_width *
349 DIV_ROUND_UP(sizes->surface_bpp, 8);
351 mode_cmd.pitches[0] = roundup(mode_cmd.pitches[0],
353 mode_cmd.pixel_format = drm_driver_legacy_fb_format(dev, sizes->surface_bpp,
354 sizes->surface_depth);
355 if (obj->size < mode_cmd.pitches[0] * mode_cmd.height)
356 return ERR_PTR(-EINVAL);
359 funcs = &drm_gem_fb_funcs;
361 return drm_gem_fb_alloc(dev, &mode_cmd, &obj, 1, funcs);
363 EXPORT_SYMBOL(drm_gem_fbdev_fb_create);