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.
35  * .. code-block:: c
50  * into the HW's framebuffer memory during an atomic update. This requires
52  * cannot be established by commit-tail functions, such as atomic_update,
55  * The helpers for shadow-buffered planes establish and release mappings,
57  * for commit-tail functions.
59  * Shadow-buffered planes can easily be enabled by using the provided macros
61  * These macros set up the plane and plane-helper callbacks to point to the
62  * shadow-buffer helpers.
64  * .. code-block:: c
78  * In the driver's atomic-update function, shadow-buffer mappings are available
82  * .. code-block:: c
87  *		struct drm_plane_state *plane_state = plane->state;
91  *		// access shadow buffer via shadow_plane_state->map
94  * A mapping address for each of the framebuffer's buffer object is stored in
100  * callbacks. Access to shadow-buffer mappings is similar to regular
103  * .. code-block:: c
117  *		// access shadow buffer via shadow_plane_state->map
126  * drm_gem_plane_helper_prepare_fb() - Prepare a GEM backed framebuffer
136  * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
137  * GEM based framebuffer drivers which have their buffers always pinned in
146 	struct dma_fence *fence = dma_fence_get(state->fence);  in drm_gem_plane_helper_prepare_fb()
151 	if (!state->fb)  in drm_gem_plane_helper_prepare_fb()
159 	 * which is important to make explicit fencing use-cases work: One  in drm_gem_plane_helper_prepare_fb()
169 	for (i = 0; i < state->fb->format->num_planes; ++i) {  in drm_gem_plane_helper_prepare_fb()
170 		struct drm_gem_object *obj = drm_gem_fb_get_obj(state->fb, i);  in drm_gem_plane_helper_prepare_fb()
174 			ret = -EINVAL;  in drm_gem_plane_helper_prepare_fb()
178 		ret = dma_resv_get_singleton(obj->resv, usage, &new);  in drm_gem_plane_helper_prepare_fb()
186 				ret = -ENOMEM;  in drm_gem_plane_helper_prepare_fb()
191 			fence = &chain->base;  in drm_gem_plane_helper_prepare_fb()
198 	dma_fence_put(state->fence);  in drm_gem_plane_helper_prepare_fb()
199 	state->fence = fence;  in drm_gem_plane_helper_prepare_fb()
209  * drm_gem_simple_display_pipe_prepare_fb - prepare_fb helper for &drm_simple_display_pipe
210  * @pipe: Simple display pipe
225 	return drm_gem_plane_helper_prepare_fb(&pipe->plane, plane_state);  in drm_gem_simple_display_pipe_prepare_fb()
230  * Shadow-buffered Planes
234  * __drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
236  * @new_shadow_plane_state: the new shadow-buffered plane state
238  * This function duplicates shadow-buffered plane state. This is helpful for drivers
250 	__drm_atomic_helper_plane_duplicate_state(plane, &new_shadow_plane_state->base);  in __drm_gem_duplicate_shadow_plane_state()
255  * drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
259  * shadow-buffered planes. It assumes the existing state to be of type
274 	struct drm_plane_state *plane_state = plane->state;  in drm_gem_duplicate_shadow_plane_state()
285 	return &new_shadow_plane_state->base;  in drm_gem_duplicate_shadow_plane_state()
290  * __drm_gem_destroy_shadow_plane_state - cleans up shadow-buffered plane state
291  * @shadow_plane_state: the shadow-buffered plane state
293  * This function cleans up shadow-buffered plane state. Helpful for drivers that
298 	__drm_atomic_helper_plane_destroy_state(&shadow_plane_state->base);  in __drm_gem_destroy_shadow_plane_state()
303  * drm_gem_destroy_shadow_plane_state - deletes shadow-buffered plane state
308  * for shadow-buffered planes. It expects that mappings of shadow buffers
323  * __drm_gem_reset_shadow_plane - resets a shadow-buffered plane
325  * @shadow_plane_state: the shadow-buffered plane state
327  * This function resets state for shadow-buffered planes. Helpful
333 	__drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);  in __drm_gem_reset_shadow_plane()
338  * drm_gem_reset_shadow_plane - resets a shadow-buffered plane
342  * shadow-buffered planes. It assumes the current plane state to be
350 	if (plane->state) {  in drm_gem_reset_shadow_plane()
351 		drm_gem_destroy_shadow_plane_state(plane, plane->state);  in drm_gem_reset_shadow_plane()
352 		plane->state = NULL; /* must be set to NULL here */  in drm_gem_reset_shadow_plane()
363  * drm_gem_prepare_shadow_fb - prepares shadow framebuffers
368  * maps all buffer objects of the plane's framebuffer into kernel address
370  * framebuffer will be synchronized as part of the atomic commit.
380 	struct drm_framebuffer *fb = plane_state->fb;  in drm_gem_prepare_shadow_fb()
390 	return drm_gem_fb_vmap(fb, shadow_plane_state->map, shadow_plane_state->data);  in drm_gem_prepare_shadow_fb()
395  * drm_gem_cleanup_shadow_fb - releases shadow framebuffers
400  * This function unmaps all buffer objects of the plane's framebuffer.
407 	struct drm_framebuffer *fb = plane_state->fb;  in drm_gem_cleanup_shadow_fb()
412 	drm_gem_fb_vunmap(fb, shadow_plane_state->map);  in drm_gem_cleanup_shadow_fb()
417  * drm_gem_simple_kms_prepare_shadow_fb - prepares shadow framebuffers
418  * @pipe: the simple display pipe
422  * maps all buffer objects of the plane's framebuffer into kernel address
424  * framebuffer will be synchronized as part of the atomic commit.
434 	return drm_gem_prepare_shadow_fb(&pipe->plane, plane_state);  in drm_gem_simple_kms_prepare_shadow_fb()
439  * drm_gem_simple_kms_cleanup_shadow_fb - releases shadow framebuffers
440  * @pipe: the simple display pipe
444  * This function unmaps all buffer objects of the plane's framebuffer.
451 	drm_gem_cleanup_shadow_fb(&pipe->plane, plane_state);  in drm_gem_simple_kms_cleanup_shadow_fb()
456  * drm_gem_simple_kms_reset_shadow_plane - resets a shadow-buffered plane
457  * @pipe: the simple display pipe
460  * for shadow-buffered planes.
464 	drm_gem_reset_shadow_plane(&pipe->plane);  in drm_gem_simple_kms_reset_shadow_plane()
469  * drm_gem_simple_kms_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
470  * @pipe: the simple display pipe
473  * for shadow-buffered planes. It does not duplicate existing mappings of the shadow
483 	return drm_gem_duplicate_shadow_plane_state(&pipe->plane);  in drm_gem_simple_kms_duplicate_shadow_plane_state()
488  * drm_gem_simple_kms_destroy_shadow_plane_state - resets shadow-buffered plane state
489  * @pipe: the simple display pipe
493  * for shadow-buffered planes. It expects that mappings of shadow buffers
499 	drm_gem_destroy_shadow_plane_state(&pipe->plane, plane_state);  in drm_gem_simple_kms_destroy_shadow_plane_state()