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