1 // SPDX-License-Identifier: GPL-2.0-or-later
3 #include <linux/dma-resv.h>
4 #include <linux/dma-fence-chain.h>
19  * The GEM atomic helpers library implements generic atomic-commit
21  * synchronization helpers, and plane state and framebuffer BO mappings
24  * Before scanout, a plane's framebuffer needs to be synchronized with
25  * possible writers that draw into the framebuffer. All drivers should
28  * the framebuffer so that the DRM core can synchronize access automatically.
32  * .. code-block:: c
42  * into the HW's framebuffer memory during an atomic update. This requires
44  * cannot be established by commit-tail functions, such as atomic_update,
47  * The helpers for shadow-buffered planes establish and release mappings,
49  * for commit-tail functions.
51  * Shadow-buffered planes can easily be enabled by using the provided macros
53  * These macros set up the plane and plane-helper callbacks to point to the
54  * shadow-buffer helpers.
56  * .. code-block:: c
70  * In the driver's atomic-update function, shadow-buffer mappings are available
74  * .. code-block:: c
79  *		struct drm_plane_state *plane_state = plane->state;
83  *		// access shadow buffer via shadow_plane_state->map
86  * A mapping address for each of the framebuffer's buffer object is stored in
92  * callbacks. Access to shadow-buffer mappings is similar to regular
95  * .. code-block:: c
109  *		// access shadow buffer via shadow_plane_state->map
118  * drm_gem_plane_helper_prepare_fb() - Prepare a GEM backed framebuffer
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
138 	struct dma_fence *fence = dma_fence_get(state->fence);  in drm_gem_plane_helper_prepare_fb()
143 	if (!state->fb)  in drm_gem_plane_helper_prepare_fb()
151 	 * which is important to make explicit fencing use-cases work: One  in drm_gem_plane_helper_prepare_fb()
161 	for (i = 0; i < state->fb->format->num_planes; ++i) {  in drm_gem_plane_helper_prepare_fb()
162 		struct drm_gem_object *obj = drm_gem_fb_get_obj(state->fb, i);  in drm_gem_plane_helper_prepare_fb()
166 			ret = -EINVAL;  in drm_gem_plane_helper_prepare_fb()
170 		ret = dma_resv_get_singleton(obj->resv, usage, &new);  in drm_gem_plane_helper_prepare_fb()
178 				ret = -ENOMEM;  in drm_gem_plane_helper_prepare_fb()
183 			fence = &chain->base;  in drm_gem_plane_helper_prepare_fb()
190 	dma_fence_put(state->fence);  in drm_gem_plane_helper_prepare_fb()
191 	state->fence = fence;  in drm_gem_plane_helper_prepare_fb()
201  * Shadow-buffered Planes
205  * __drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
207  * @new_shadow_plane_state: the new shadow-buffered plane state
209  * This function duplicates shadow-buffered plane state. This is helpful for drivers
221 	__drm_atomic_helper_plane_duplicate_state(plane, &new_shadow_plane_state->base);  in __drm_gem_duplicate_shadow_plane_state()
226  * drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
230  * shadow-buffered planes. It assumes the existing state to be of type
245 	struct drm_plane_state *plane_state = plane->state;  in drm_gem_duplicate_shadow_plane_state()
256 	return &new_shadow_plane_state->base;  in drm_gem_duplicate_shadow_plane_state()
261  * __drm_gem_destroy_shadow_plane_state - cleans up shadow-buffered plane state
262  * @shadow_plane_state: the shadow-buffered plane state
264  * This function cleans up shadow-buffered plane state. Helpful for drivers that
269 	__drm_atomic_helper_plane_destroy_state(&shadow_plane_state->base);  in __drm_gem_destroy_shadow_plane_state()
274  * drm_gem_destroy_shadow_plane_state - deletes shadow-buffered plane state
279  * for shadow-buffered planes. It expects that mappings of shadow buffers
294  * __drm_gem_reset_shadow_plane - resets a shadow-buffered plane
296  * @shadow_plane_state: the shadow-buffered plane state
298  * This function resets state for shadow-buffered planes. Helpful
304 	__drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);  in __drm_gem_reset_shadow_plane()
309  * drm_gem_reset_shadow_plane - resets a shadow-buffered plane
313  * shadow-buffered planes. It assumes the current plane state to be
321 	if (plane->state) {  in drm_gem_reset_shadow_plane()
322 		drm_gem_destroy_shadow_plane_state(plane, plane->state);  in drm_gem_reset_shadow_plane()
323 		plane->state = NULL; /* must be set to NULL here */  in drm_gem_reset_shadow_plane()
334  * drm_gem_begin_shadow_fb_access - prepares shadow framebuffers for CPU access
339  * maps all buffer objects of the plane's framebuffer into kernel address
351 	struct drm_framebuffer *fb = plane_state->fb;  in drm_gem_begin_shadow_fb_access()
356 	return drm_gem_fb_vmap(fb, shadow_plane_state->map, shadow_plane_state->data);  in drm_gem_begin_shadow_fb_access()
361  * drm_gem_end_shadow_fb_access - releases shadow framebuffers from CPU access
373 	struct drm_framebuffer *fb = plane_state->fb;  in drm_gem_end_shadow_fb_access()
378 	drm_gem_fb_vunmap(fb, shadow_plane_state->map);  in drm_gem_end_shadow_fb_access()
383  * drm_gem_simple_kms_begin_shadow_fb_access - prepares shadow framebuffers for CPU access
384  * @pipe: the simple display pipe
398 	return drm_gem_begin_shadow_fb_access(&pipe->plane, plane_state);  in drm_gem_simple_kms_begin_shadow_fb_access()
403  * drm_gem_simple_kms_end_shadow_fb_access - releases shadow framebuffers from CPU access
404  * @pipe: the simple display pipe
416 	drm_gem_end_shadow_fb_access(&pipe->plane, plane_state);  in drm_gem_simple_kms_end_shadow_fb_access()
421  * drm_gem_simple_kms_reset_shadow_plane - resets a shadow-buffered plane
422  * @pipe: the simple display pipe
425  * for shadow-buffered planes.
429 	drm_gem_reset_shadow_plane(&pipe->plane);  in drm_gem_simple_kms_reset_shadow_plane()
434  * drm_gem_simple_kms_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
435  * @pipe: the simple display pipe
438  * for shadow-buffered planes. It does not duplicate existing mappings of the shadow
448 	return drm_gem_duplicate_shadow_plane_state(&pipe->plane);  in drm_gem_simple_kms_duplicate_shadow_plane_state()
453  * drm_gem_simple_kms_destroy_shadow_plane_state - resets shadow-buffered plane state
454  * @pipe: the simple display pipe
458  * for shadow-buffered planes. It expects that mappings of shadow buffers
464 	drm_gem_destroy_shadow_plane_state(&pipe->plane, plane_state);  in drm_gem_simple_kms_destroy_shadow_plane_state()