Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-or-later
2 :
3 : #include <linux/dma-resv.h>
4 : #include <linux/dma-fence-chain.h>
5 :
6 : #include <drm/drm_atomic_state_helper.h>
7 : #include <drm/drm_atomic_uapi.h>
8 : #include <drm/drm_gem.h>
9 : #include <drm/drm_gem_atomic_helper.h>
10 : #include <drm/drm_gem_framebuffer_helper.h>
11 : #include <drm/drm_simple_kms_helper.h>
12 :
13 : #include "drm_internal.h"
14 :
15 : /**
16 : * DOC: overview
17 : *
18 : * The GEM atomic helpers library implements generic atomic-commit
19 : * functions for drivers that use GEM objects. Currently, it provides
20 : * synchronization helpers, and plane state and framebuffer BO mappings
21 : * for planes with shadow buffers.
22 : *
23 : * Before scanout, a plane's framebuffer needs to be synchronized with
24 : * possible writers that draw into the framebuffer. All drivers should
25 : * call drm_gem_plane_helper_prepare_fb() from their implementation of
26 : * struct &drm_plane_helper.prepare_fb . It sets the plane's fence from
27 : * the framebuffer so that the DRM core can synchronize access automatically.
28 : *
29 : * drm_gem_plane_helper_prepare_fb() can also be used directly as
30 : * implementation of prepare_fb. For drivers based on
31 : * struct drm_simple_display_pipe, drm_gem_simple_display_pipe_prepare_fb()
32 : * provides equivalent functionality.
33 : *
34 : * .. code-block:: c
35 : *
36 : * #include <drm/drm_gem_atomic_helper.h>
37 : *
38 : * struct drm_plane_helper_funcs driver_plane_helper_funcs = {
39 : * ...,
40 : * . prepare_fb = drm_gem_plane_helper_prepare_fb,
41 : * };
42 : *
43 : * struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
44 : * ...,
45 : * . prepare_fb = drm_gem_simple_display_pipe_prepare_fb,
46 : * };
47 : *
48 : * A driver using a shadow buffer copies the content of the shadow buffers
49 : * into the HW's framebuffer memory during an atomic update. This requires
50 : * a mapping of the shadow buffer into kernel address space. The mappings
51 : * cannot be established by commit-tail functions, such as atomic_update,
52 : * as this would violate locking rules around dma_buf_vmap().
53 : *
54 : * The helpers for shadow-buffered planes establish and release mappings,
55 : * and provide struct drm_shadow_plane_state, which stores the plane's mapping
56 : * for commit-tail functions.
57 : *
58 : * Shadow-buffered planes can easily be enabled by using the provided macros
59 : * %DRM_GEM_SHADOW_PLANE_FUNCS and %DRM_GEM_SHADOW_PLANE_HELPER_FUNCS.
60 : * These macros set up the plane and plane-helper callbacks to point to the
61 : * shadow-buffer helpers.
62 : *
63 : * .. code-block:: c
64 : *
65 : * #include <drm/drm_gem_atomic_helper.h>
66 : *
67 : * struct drm_plane_funcs driver_plane_funcs = {
68 : * ...,
69 : * DRM_GEM_SHADOW_PLANE_FUNCS,
70 : * };
71 : *
72 : * struct drm_plane_helper_funcs driver_plane_helper_funcs = {
73 : * ...,
74 : * DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
75 : * };
76 : *
77 : * In the driver's atomic-update function, shadow-buffer mappings are available
78 : * from the plane state. Use to_drm_shadow_plane_state() to upcast from
79 : * struct drm_plane_state.
80 : *
81 : * .. code-block:: c
82 : *
83 : * void driver_plane_atomic_update(struct drm_plane *plane,
84 : * struct drm_plane_state *old_plane_state)
85 : * {
86 : * struct drm_plane_state *plane_state = plane->state;
87 : * struct drm_shadow_plane_state *shadow_plane_state =
88 : * to_drm_shadow_plane_state(plane_state);
89 : *
90 : * // access shadow buffer via shadow_plane_state->map
91 : * }
92 : *
93 : * A mapping address for each of the framebuffer's buffer object is stored in
94 : * struct &drm_shadow_plane_state.map. The mappings are valid while the state
95 : * is being used.
96 : *
97 : * Drivers that use struct drm_simple_display_pipe can use
98 : * %DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS to initialize the rsp
99 : * callbacks. Access to shadow-buffer mappings is similar to regular
100 : * atomic_update.
101 : *
102 : * .. code-block:: c
103 : *
104 : * struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
105 : * ...,
106 : * DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS,
107 : * };
108 : *
109 : * void driver_pipe_enable(struct drm_simple_display_pipe *pipe,
110 : * struct drm_crtc_state *crtc_state,
111 : * struct drm_plane_state *plane_state)
112 : * {
113 : * struct drm_shadow_plane_state *shadow_plane_state =
114 : * to_drm_shadow_plane_state(plane_state);
115 : *
116 : * // access shadow buffer via shadow_plane_state->map
117 : * }
118 : */
119 :
120 : /*
121 : * Plane Helpers
122 : */
123 :
124 : /**
125 : * drm_gem_plane_helper_prepare_fb() - Prepare a GEM backed framebuffer
126 : * @plane: Plane
127 : * @state: Plane state the fence will be attached to
128 : *
129 : * This function extracts the exclusive fence from &drm_gem_object.resv and
130 : * attaches it to plane state for the atomic helper to wait on. This is
131 : * necessary to correctly implement implicit synchronization for any buffers
132 : * shared as a struct &dma_buf. This function can be used as the
133 : * &drm_plane_helper_funcs.prepare_fb callback.
134 : *
135 : * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
136 : * GEM based framebuffer drivers which have their buffers always pinned in
137 : * memory.
138 : *
139 : * This function is the default implementation for GEM drivers of
140 : * &drm_plane_helper_funcs.prepare_fb if no callback is provided.
141 : */
142 0 : int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane,
143 : struct drm_plane_state *state)
144 : {
145 0 : struct dma_fence *fence = dma_fence_get(state->fence);
146 : enum dma_resv_usage usage;
147 : size_t i;
148 : int ret;
149 :
150 0 : if (!state->fb)
151 : return 0;
152 :
153 : /*
154 : * Only add the kernel fences here if there is already a fence set via
155 : * explicit fencing interfaces on the atomic ioctl.
156 : *
157 : * This way explicit fencing can be used to overrule implicit fencing,
158 : * which is important to make explicit fencing use-cases work: One
159 : * example is using one buffer for 2 screens with different refresh
160 : * rates. Implicit fencing will clamp rendering to the refresh rate of
161 : * the slower screen, whereas explicit fence allows 2 independent
162 : * render and display loops on a single buffer. If a driver allows
163 : * obeys both implicit and explicit fences for plane updates, then it
164 : * will break all the benefits of explicit fencing.
165 : */
166 0 : usage = fence ? DMA_RESV_USAGE_KERNEL : DMA_RESV_USAGE_WRITE;
167 :
168 0 : for (i = 0; i < state->fb->format->num_planes; ++i) {
169 0 : struct drm_gem_object *obj = drm_gem_fb_get_obj(state->fb, i);
170 : struct dma_fence *new;
171 :
172 0 : if (WARN_ON_ONCE(!obj))
173 0 : continue;
174 :
175 0 : ret = dma_resv_get_singleton(obj->resv, usage, &new);
176 0 : if (ret)
177 : goto error;
178 :
179 0 : if (new && fence) {
180 0 : struct dma_fence_chain *chain = dma_fence_chain_alloc();
181 :
182 0 : if (!chain) {
183 : ret = -ENOMEM;
184 : goto error;
185 : }
186 :
187 0 : dma_fence_chain_init(chain, fence, new, 1);
188 0 : fence = &chain->base;
189 :
190 0 : } else if (new) {
191 0 : fence = new;
192 : }
193 : }
194 :
195 0 : dma_fence_put(state->fence);
196 0 : state->fence = fence;
197 0 : return 0;
198 :
199 : error:
200 : dma_fence_put(fence);
201 : return ret;
202 : }
203 : EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb);
204 :
205 : /**
206 : * drm_gem_simple_display_pipe_prepare_fb - prepare_fb helper for &drm_simple_display_pipe
207 : * @pipe: Simple display pipe
208 : * @plane_state: Plane state
209 : *
210 : * This function uses drm_gem_plane_helper_prepare_fb() to extract the fences
211 : * from &drm_gem_object.resv and attaches them to the plane state for the atomic
212 : * helper to wait on. This is necessary to correctly implement implicit
213 : * synchronization for any buffers shared as a struct &dma_buf. Drivers can use
214 : * this as their &drm_simple_display_pipe_funcs.prepare_fb callback.
215 : *
216 : * See drm_gem_plane_helper_prepare_fb() for a discussion of implicit and
217 : * explicit fencing in atomic modeset updates.
218 : */
219 0 : int drm_gem_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
220 : struct drm_plane_state *plane_state)
221 : {
222 0 : return drm_gem_plane_helper_prepare_fb(&pipe->plane, plane_state);
223 : }
224 : EXPORT_SYMBOL(drm_gem_simple_display_pipe_prepare_fb);
225 :
226 : /*
227 : * Shadow-buffered Planes
228 : */
229 :
230 : /**
231 : * __drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
232 : * @plane: the plane
233 : * @new_shadow_plane_state: the new shadow-buffered plane state
234 : *
235 : * This function duplicates shadow-buffered plane state. This is helpful for drivers
236 : * that subclass struct drm_shadow_plane_state.
237 : *
238 : * The function does not duplicate existing mappings of the shadow buffers.
239 : * Mappings are maintained during the atomic commit by the plane's prepare_fb
240 : * and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
241 : * for corresponding helpers.
242 : */
243 : void
244 0 : __drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane,
245 : struct drm_shadow_plane_state *new_shadow_plane_state)
246 : {
247 0 : __drm_atomic_helper_plane_duplicate_state(plane, &new_shadow_plane_state->base);
248 0 : }
249 : EXPORT_SYMBOL(__drm_gem_duplicate_shadow_plane_state);
250 :
251 : /**
252 : * drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
253 : * @plane: the plane
254 : *
255 : * This function implements struct &drm_plane_funcs.atomic_duplicate_state for
256 : * shadow-buffered planes. It assumes the existing state to be of type
257 : * struct drm_shadow_plane_state and it allocates the new state to be of this
258 : * type.
259 : *
260 : * The function does not duplicate existing mappings of the shadow buffers.
261 : * Mappings are maintained during the atomic commit by the plane's prepare_fb
262 : * and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
263 : * for corresponding helpers.
264 : *
265 : * Returns:
266 : * A pointer to a new plane state on success, or NULL otherwise.
267 : */
268 : struct drm_plane_state *
269 0 : drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane)
270 : {
271 0 : struct drm_plane_state *plane_state = plane->state;
272 : struct drm_shadow_plane_state *new_shadow_plane_state;
273 :
274 0 : if (!plane_state)
275 : return NULL;
276 :
277 0 : new_shadow_plane_state = kzalloc(sizeof(*new_shadow_plane_state), GFP_KERNEL);
278 0 : if (!new_shadow_plane_state)
279 : return NULL;
280 0 : __drm_gem_duplicate_shadow_plane_state(plane, new_shadow_plane_state);
281 :
282 0 : return &new_shadow_plane_state->base;
283 : }
284 : EXPORT_SYMBOL(drm_gem_duplicate_shadow_plane_state);
285 :
286 : /**
287 : * __drm_gem_destroy_shadow_plane_state - cleans up shadow-buffered plane state
288 : * @shadow_plane_state: the shadow-buffered plane state
289 : *
290 : * This function cleans up shadow-buffered plane state. Helpful for drivers that
291 : * subclass struct drm_shadow_plane_state.
292 : */
293 0 : void __drm_gem_destroy_shadow_plane_state(struct drm_shadow_plane_state *shadow_plane_state)
294 : {
295 0 : __drm_atomic_helper_plane_destroy_state(&shadow_plane_state->base);
296 0 : }
297 : EXPORT_SYMBOL(__drm_gem_destroy_shadow_plane_state);
298 :
299 : /**
300 : * drm_gem_destroy_shadow_plane_state - deletes shadow-buffered plane state
301 : * @plane: the plane
302 : * @plane_state: the plane state of type struct drm_shadow_plane_state
303 : *
304 : * This function implements struct &drm_plane_funcs.atomic_destroy_state
305 : * for shadow-buffered planes. It expects that mappings of shadow buffers
306 : * have been released already.
307 : */
308 0 : void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
309 : struct drm_plane_state *plane_state)
310 : {
311 0 : struct drm_shadow_plane_state *shadow_plane_state =
312 : to_drm_shadow_plane_state(plane_state);
313 :
314 0 : __drm_gem_destroy_shadow_plane_state(shadow_plane_state);
315 0 : kfree(shadow_plane_state);
316 0 : }
317 : EXPORT_SYMBOL(drm_gem_destroy_shadow_plane_state);
318 :
319 : /**
320 : * __drm_gem_reset_shadow_plane - resets a shadow-buffered plane
321 : * @plane: the plane
322 : * @shadow_plane_state: the shadow-buffered plane state
323 : *
324 : * This function resets state for shadow-buffered planes. Helpful
325 : * for drivers that subclass struct drm_shadow_plane_state.
326 : */
327 0 : void __drm_gem_reset_shadow_plane(struct drm_plane *plane,
328 : struct drm_shadow_plane_state *shadow_plane_state)
329 : {
330 0 : __drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);
331 0 : }
332 : EXPORT_SYMBOL(__drm_gem_reset_shadow_plane);
333 :
334 : /**
335 : * drm_gem_reset_shadow_plane - resets a shadow-buffered plane
336 : * @plane: the plane
337 : *
338 : * This function implements struct &drm_plane_funcs.reset_plane for
339 : * shadow-buffered planes. It assumes the current plane state to be
340 : * of type struct drm_shadow_plane and it allocates the new state of
341 : * this type.
342 : */
343 0 : void drm_gem_reset_shadow_plane(struct drm_plane *plane)
344 : {
345 : struct drm_shadow_plane_state *shadow_plane_state;
346 :
347 0 : if (plane->state) {
348 0 : drm_gem_destroy_shadow_plane_state(plane, plane->state);
349 0 : plane->state = NULL; /* must be set to NULL here */
350 : }
351 :
352 0 : shadow_plane_state = kzalloc(sizeof(*shadow_plane_state), GFP_KERNEL);
353 0 : if (!shadow_plane_state)
354 : return;
355 : __drm_gem_reset_shadow_plane(plane, shadow_plane_state);
356 : }
357 : EXPORT_SYMBOL(drm_gem_reset_shadow_plane);
358 :
359 : /**
360 : * drm_gem_prepare_shadow_fb - prepares shadow framebuffers
361 : * @plane: the plane
362 : * @plane_state: the plane state of type struct drm_shadow_plane_state
363 : *
364 : * This function implements struct &drm_plane_helper_funcs.prepare_fb. It
365 : * maps all buffer objects of the plane's framebuffer into kernel address
366 : * space and stores them in &struct drm_shadow_plane_state.map. The
367 : * framebuffer will be synchronized as part of the atomic commit.
368 : *
369 : * See drm_gem_cleanup_shadow_fb() for cleanup.
370 : *
371 : * Returns:
372 : * 0 on success, or a negative errno code otherwise.
373 : */
374 0 : int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
375 : {
376 0 : struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
377 0 : struct drm_framebuffer *fb = plane_state->fb;
378 : int ret;
379 :
380 0 : if (!fb)
381 : return 0;
382 :
383 0 : ret = drm_gem_plane_helper_prepare_fb(plane, plane_state);
384 0 : if (ret)
385 : return ret;
386 :
387 0 : return drm_gem_fb_vmap(fb, shadow_plane_state->map, shadow_plane_state->data);
388 : }
389 : EXPORT_SYMBOL(drm_gem_prepare_shadow_fb);
390 :
391 : /**
392 : * drm_gem_cleanup_shadow_fb - releases shadow framebuffers
393 : * @plane: the plane
394 : * @plane_state: the plane state of type struct drm_shadow_plane_state
395 : *
396 : * This function implements struct &drm_plane_helper_funcs.cleanup_fb.
397 : * This function unmaps all buffer objects of the plane's framebuffer.
398 : *
399 : * See drm_gem_prepare_shadow_fb() for more information.
400 : */
401 0 : void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
402 : {
403 0 : struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
404 0 : struct drm_framebuffer *fb = plane_state->fb;
405 :
406 0 : if (!fb)
407 : return;
408 :
409 0 : drm_gem_fb_vunmap(fb, shadow_plane_state->map);
410 : }
411 : EXPORT_SYMBOL(drm_gem_cleanup_shadow_fb);
412 :
413 : /**
414 : * drm_gem_simple_kms_prepare_shadow_fb - prepares shadow framebuffers
415 : * @pipe: the simple display pipe
416 : * @plane_state: the plane state of type struct drm_shadow_plane_state
417 : *
418 : * This function implements struct drm_simple_display_funcs.prepare_fb. It
419 : * maps all buffer objects of the plane's framebuffer into kernel address
420 : * space and stores them in struct drm_shadow_plane_state.map. The
421 : * framebuffer will be synchronized as part of the atomic commit.
422 : *
423 : * See drm_gem_simple_kms_cleanup_shadow_fb() for cleanup.
424 : *
425 : * Returns:
426 : * 0 on success, or a negative errno code otherwise.
427 : */
428 0 : int drm_gem_simple_kms_prepare_shadow_fb(struct drm_simple_display_pipe *pipe,
429 : struct drm_plane_state *plane_state)
430 : {
431 0 : return drm_gem_prepare_shadow_fb(&pipe->plane, plane_state);
432 : }
433 : EXPORT_SYMBOL(drm_gem_simple_kms_prepare_shadow_fb);
434 :
435 : /**
436 : * drm_gem_simple_kms_cleanup_shadow_fb - releases shadow framebuffers
437 : * @pipe: the simple display pipe
438 : * @plane_state: the plane state of type struct drm_shadow_plane_state
439 : *
440 : * This function implements struct drm_simple_display_funcs.cleanup_fb.
441 : * This function unmaps all buffer objects of the plane's framebuffer.
442 : *
443 : * See drm_gem_simple_kms_prepare_shadow_fb().
444 : */
445 0 : void drm_gem_simple_kms_cleanup_shadow_fb(struct drm_simple_display_pipe *pipe,
446 : struct drm_plane_state *plane_state)
447 : {
448 0 : drm_gem_cleanup_shadow_fb(&pipe->plane, plane_state);
449 0 : }
450 : EXPORT_SYMBOL(drm_gem_simple_kms_cleanup_shadow_fb);
451 :
452 : /**
453 : * drm_gem_simple_kms_reset_shadow_plane - resets a shadow-buffered plane
454 : * @pipe: the simple display pipe
455 : *
456 : * This function implements struct drm_simple_display_funcs.reset_plane
457 : * for shadow-buffered planes.
458 : */
459 0 : void drm_gem_simple_kms_reset_shadow_plane(struct drm_simple_display_pipe *pipe)
460 : {
461 0 : drm_gem_reset_shadow_plane(&pipe->plane);
462 0 : }
463 : EXPORT_SYMBOL(drm_gem_simple_kms_reset_shadow_plane);
464 :
465 : /**
466 : * drm_gem_simple_kms_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
467 : * @pipe: the simple display pipe
468 : *
469 : * This function implements struct drm_simple_display_funcs.duplicate_plane_state
470 : * for shadow-buffered planes. It does not duplicate existing mappings of the shadow
471 : * buffers. Mappings are maintained during the atomic commit by the plane's prepare_fb
472 : * and cleanup_fb helpers.
473 : *
474 : * Returns:
475 : * A pointer to a new plane state on success, or NULL otherwise.
476 : */
477 : struct drm_plane_state *
478 0 : drm_gem_simple_kms_duplicate_shadow_plane_state(struct drm_simple_display_pipe *pipe)
479 : {
480 0 : return drm_gem_duplicate_shadow_plane_state(&pipe->plane);
481 : }
482 : EXPORT_SYMBOL(drm_gem_simple_kms_duplicate_shadow_plane_state);
483 :
484 : /**
485 : * drm_gem_simple_kms_destroy_shadow_plane_state - resets shadow-buffered plane state
486 : * @pipe: the simple display pipe
487 : * @plane_state: the plane state of type struct drm_shadow_plane_state
488 : *
489 : * This function implements struct drm_simple_display_funcs.destroy_plane_state
490 : * for shadow-buffered planes. It expects that mappings of shadow buffers
491 : * have been released already.
492 : */
493 0 : void drm_gem_simple_kms_destroy_shadow_plane_state(struct drm_simple_display_pipe *pipe,
494 : struct drm_plane_state *plane_state)
495 : {
496 0 : drm_gem_destroy_shadow_plane_state(&pipe->plane, plane_state);
497 0 : }
498 : EXPORT_SYMBOL(drm_gem_simple_kms_destroy_shadow_plane_state);
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