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![Christian König](/assets/img/avatar_default.png)
Makes the handling a bit more complex, but avoids the use of dma_resv_get_excl_unlocked(). v2: improve coding and documentation v3: adjust the TODO comment as suggested by Daniel Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20211005113742.1101-25-christian.koenig@amd.com
463 lines
16 KiB
C
463 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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#include <linux/dma-resv.h>
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#include <drm/drm_atomic_state_helper.h>
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#include <drm/drm_atomic_uapi.h>
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#include <drm/drm_gem.h>
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#include <drm/drm_gem_atomic_helper.h>
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#include <drm/drm_gem_framebuffer_helper.h>
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#include <drm/drm_simple_kms_helper.h>
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#include "drm_internal.h"
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/**
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* DOC: overview
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*
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* The GEM atomic helpers library implements generic atomic-commit
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* functions for drivers that use GEM objects. Currently, it provides
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* synchronization helpers, and plane state and framebuffer BO mappings
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* for planes with shadow buffers.
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*
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* Before scanout, a plane's framebuffer needs to be synchronized with
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* possible writers that draw into the framebuffer. All drivers should
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* call drm_gem_plane_helper_prepare_fb() from their implementation of
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* struct &drm_plane_helper.prepare_fb . It sets the plane's fence from
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* the framebuffer so that the DRM core can synchronize access automatically.
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*
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* drm_gem_plane_helper_prepare_fb() can also be used directly as
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* implementation of prepare_fb. For drivers based on
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* struct drm_simple_display_pipe, drm_gem_simple_display_pipe_prepare_fb()
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* provides equivalent functionality.
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*
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* .. code-block:: c
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*
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* #include <drm/drm_gem_atomic_helper.h>
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*
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* struct drm_plane_helper_funcs driver_plane_helper_funcs = {
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* ...,
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* . prepare_fb = drm_gem_plane_helper_prepare_fb,
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* };
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*
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* struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
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* ...,
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* . prepare_fb = drm_gem_simple_display_pipe_prepare_fb,
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* };
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*
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* A driver using a shadow buffer copies the content of the shadow buffers
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* into the HW's framebuffer memory during an atomic update. This requires
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* a mapping of the shadow buffer into kernel address space. The mappings
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* cannot be established by commit-tail functions, such as atomic_update,
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* as this would violate locking rules around dma_buf_vmap().
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*
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* The helpers for shadow-buffered planes establish and release mappings,
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* and provide struct drm_shadow_plane_state, which stores the plane's mapping
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* for commit-tail functions.
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*
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* Shadow-buffered planes can easily be enabled by using the provided macros
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* %DRM_GEM_SHADOW_PLANE_FUNCS and %DRM_GEM_SHADOW_PLANE_HELPER_FUNCS.
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* These macros set up the plane and plane-helper callbacks to point to the
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* shadow-buffer helpers.
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*
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* .. code-block:: c
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*
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* #include <drm/drm_gem_atomic_helper.h>
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*
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* struct drm_plane_funcs driver_plane_funcs = {
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* ...,
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* DRM_GEM_SHADOW_PLANE_FUNCS,
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* };
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*
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* struct drm_plane_helper_funcs driver_plane_helper_funcs = {
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* ...,
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* DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
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* };
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*
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* In the driver's atomic-update function, shadow-buffer mappings are available
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* from the plane state. Use to_drm_shadow_plane_state() to upcast from
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* struct drm_plane_state.
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*
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* .. code-block:: c
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*
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* void driver_plane_atomic_update(struct drm_plane *plane,
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* struct drm_plane_state *old_plane_state)
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* {
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* struct drm_plane_state *plane_state = plane->state;
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* struct drm_shadow_plane_state *shadow_plane_state =
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* to_drm_shadow_plane_state(plane_state);
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*
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* // access shadow buffer via shadow_plane_state->map
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* }
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*
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* A mapping address for each of the framebuffer's buffer object is stored in
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* struct &drm_shadow_plane_state.map. The mappings are valid while the state
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* is being used.
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*
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* Drivers that use struct drm_simple_display_pipe can use
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* %DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS to initialize the rsp
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* callbacks. Access to shadow-buffer mappings is similar to regular
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* atomic_update.
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*
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* .. code-block:: c
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*
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* struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
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* ...,
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* DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS,
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* };
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*
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* void driver_pipe_enable(struct drm_simple_display_pipe *pipe,
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* struct drm_crtc_state *crtc_state,
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* struct drm_plane_state *plane_state)
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* {
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* struct drm_shadow_plane_state *shadow_plane_state =
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* to_drm_shadow_plane_state(plane_state);
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*
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* // access shadow buffer via shadow_plane_state->map
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* }
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*/
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/*
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* Plane Helpers
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*/
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/**
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* drm_gem_plane_helper_prepare_fb() - Prepare a GEM backed framebuffer
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* @plane: Plane
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* @state: Plane state the fence will be attached to
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*
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* This function extracts the exclusive fence from &drm_gem_object.resv and
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* attaches it to plane state for the atomic helper to wait on. This is
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* necessary to correctly implement implicit synchronization for any buffers
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* shared as a struct &dma_buf. This function can be used as the
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* &drm_plane_helper_funcs.prepare_fb callback.
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*
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* There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
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* GEM based framebuffer drivers which have their buffers always pinned in
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* memory.
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*
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* This function is the default implementation for GEM drivers of
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* &drm_plane_helper_funcs.prepare_fb if no callback is provided.
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*
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* See drm_atomic_set_fence_for_plane() for a discussion of implicit and
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* explicit fencing in atomic modeset updates.
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*/
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int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
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{
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struct dma_resv_iter cursor;
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struct drm_gem_object *obj;
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struct dma_fence *fence;
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if (!state->fb)
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return 0;
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obj = drm_gem_fb_get_obj(state->fb, 0);
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dma_resv_iter_begin(&cursor, obj->resv, false);
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dma_resv_for_each_fence_unlocked(&cursor, fence) {
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/* TODO: Currently there should be only one write fence, so this
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* here works fine. But drm_atomic_set_fence_for_plane() should
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* be changed to be able to handle more fences in general for
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* multiple BOs per fb anyway. */
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dma_fence_get(fence);
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break;
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}
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dma_resv_iter_end(&cursor);
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drm_atomic_set_fence_for_plane(state, fence);
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return 0;
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}
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EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb);
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/**
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* drm_gem_simple_display_pipe_prepare_fb - prepare_fb helper for &drm_simple_display_pipe
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* @pipe: Simple display pipe
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* @plane_state: Plane state
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*
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* This function uses drm_gem_plane_helper_prepare_fb() to extract the exclusive fence
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* from &drm_gem_object.resv and attaches it to plane state for the atomic
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* helper to wait on. This is necessary to correctly implement implicit
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* synchronization for any buffers shared as a struct &dma_buf. Drivers can use
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* this as their &drm_simple_display_pipe_funcs.prepare_fb callback.
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*
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* See drm_atomic_set_fence_for_plane() for a discussion of implicit and
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* explicit fencing in atomic modeset updates.
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*/
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int drm_gem_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
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struct drm_plane_state *plane_state)
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{
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return drm_gem_plane_helper_prepare_fb(&pipe->plane, plane_state);
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}
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EXPORT_SYMBOL(drm_gem_simple_display_pipe_prepare_fb);
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/*
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* Shadow-buffered Planes
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*/
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/**
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* __drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
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* @plane: the plane
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* @new_shadow_plane_state: the new shadow-buffered plane state
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*
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* This function duplicates shadow-buffered plane state. This is helpful for drivers
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* that subclass struct drm_shadow_plane_state.
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*
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* The function does not duplicate existing mappings of the shadow buffers.
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* Mappings are maintained during the atomic commit by the plane's prepare_fb
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* and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
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* for corresponding helpers.
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*/
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void
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__drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane,
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struct drm_shadow_plane_state *new_shadow_plane_state)
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{
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__drm_atomic_helper_plane_duplicate_state(plane, &new_shadow_plane_state->base);
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}
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EXPORT_SYMBOL(__drm_gem_duplicate_shadow_plane_state);
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/**
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* drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
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* @plane: the plane
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*
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* This function implements struct &drm_plane_funcs.atomic_duplicate_state for
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* shadow-buffered planes. It assumes the existing state to be of type
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* struct drm_shadow_plane_state and it allocates the new state to be of this
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* type.
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*
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* The function does not duplicate existing mappings of the shadow buffers.
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* Mappings are maintained during the atomic commit by the plane's prepare_fb
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* and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
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* for corresponding helpers.
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*
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* Returns:
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* A pointer to a new plane state on success, or NULL otherwise.
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*/
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struct drm_plane_state *
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drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane)
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{
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struct drm_plane_state *plane_state = plane->state;
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struct drm_shadow_plane_state *new_shadow_plane_state;
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if (!plane_state)
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return NULL;
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new_shadow_plane_state = kzalloc(sizeof(*new_shadow_plane_state), GFP_KERNEL);
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if (!new_shadow_plane_state)
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return NULL;
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__drm_gem_duplicate_shadow_plane_state(plane, new_shadow_plane_state);
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return &new_shadow_plane_state->base;
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}
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EXPORT_SYMBOL(drm_gem_duplicate_shadow_plane_state);
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/**
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* __drm_gem_destroy_shadow_plane_state - cleans up shadow-buffered plane state
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* @shadow_plane_state: the shadow-buffered plane state
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*
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* This function cleans up shadow-buffered plane state. Helpful for drivers that
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* subclass struct drm_shadow_plane_state.
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*/
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void __drm_gem_destroy_shadow_plane_state(struct drm_shadow_plane_state *shadow_plane_state)
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{
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__drm_atomic_helper_plane_destroy_state(&shadow_plane_state->base);
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}
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EXPORT_SYMBOL(__drm_gem_destroy_shadow_plane_state);
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/**
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* drm_gem_destroy_shadow_plane_state - deletes shadow-buffered plane state
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* @plane: the plane
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* @plane_state: the plane state of type struct drm_shadow_plane_state
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*
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* This function implements struct &drm_plane_funcs.atomic_destroy_state
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* for shadow-buffered planes. It expects that mappings of shadow buffers
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* have been released already.
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*/
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void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
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struct drm_plane_state *plane_state)
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{
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struct drm_shadow_plane_state *shadow_plane_state =
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to_drm_shadow_plane_state(plane_state);
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__drm_gem_destroy_shadow_plane_state(shadow_plane_state);
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kfree(shadow_plane_state);
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}
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EXPORT_SYMBOL(drm_gem_destroy_shadow_plane_state);
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/**
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* __drm_gem_reset_shadow_plane - resets a shadow-buffered plane
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* @plane: the plane
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* @shadow_plane_state: the shadow-buffered plane state
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*
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* This function resets state for shadow-buffered planes. Helpful
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* for drivers that subclass struct drm_shadow_plane_state.
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*/
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void __drm_gem_reset_shadow_plane(struct drm_plane *plane,
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struct drm_shadow_plane_state *shadow_plane_state)
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{
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__drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);
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}
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EXPORT_SYMBOL(__drm_gem_reset_shadow_plane);
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/**
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* drm_gem_reset_shadow_plane - resets a shadow-buffered plane
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* @plane: the plane
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*
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* This function implements struct &drm_plane_funcs.reset_plane for
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* shadow-buffered planes. It assumes the current plane state to be
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* of type struct drm_shadow_plane and it allocates the new state of
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* this type.
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*/
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void drm_gem_reset_shadow_plane(struct drm_plane *plane)
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{
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struct drm_shadow_plane_state *shadow_plane_state;
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if (plane->state) {
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drm_gem_destroy_shadow_plane_state(plane, plane->state);
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plane->state = NULL; /* must be set to NULL here */
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}
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shadow_plane_state = kzalloc(sizeof(*shadow_plane_state), GFP_KERNEL);
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if (!shadow_plane_state)
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return;
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__drm_gem_reset_shadow_plane(plane, shadow_plane_state);
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}
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EXPORT_SYMBOL(drm_gem_reset_shadow_plane);
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/**
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* drm_gem_prepare_shadow_fb - prepares shadow framebuffers
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* @plane: the plane
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* @plane_state: the plane state of type struct drm_shadow_plane_state
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*
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* This function implements struct &drm_plane_helper_funcs.prepare_fb. It
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* maps all buffer objects of the plane's framebuffer into kernel address
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* space and stores them in &struct drm_shadow_plane_state.map. The
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* framebuffer will be synchronized as part of the atomic commit.
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*
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* See drm_gem_cleanup_shadow_fb() for cleanup.
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*
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* Returns:
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* 0 on success, or a negative errno code otherwise.
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*/
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int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
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{
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struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
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struct drm_framebuffer *fb = plane_state->fb;
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int ret;
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if (!fb)
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return 0;
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ret = drm_gem_plane_helper_prepare_fb(plane, plane_state);
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if (ret)
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return ret;
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return drm_gem_fb_vmap(fb, shadow_plane_state->map, shadow_plane_state->data);
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}
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EXPORT_SYMBOL(drm_gem_prepare_shadow_fb);
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/**
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* drm_gem_cleanup_shadow_fb - releases shadow framebuffers
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* @plane: the plane
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* @plane_state: the plane state of type struct drm_shadow_plane_state
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*
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* This function implements struct &drm_plane_helper_funcs.cleanup_fb.
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* This function unmaps all buffer objects of the plane's framebuffer.
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*
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* See drm_gem_prepare_shadow_fb() for more information.
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*/
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void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
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{
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struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
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struct drm_framebuffer *fb = plane_state->fb;
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if (!fb)
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return;
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drm_gem_fb_vunmap(fb, shadow_plane_state->map);
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}
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EXPORT_SYMBOL(drm_gem_cleanup_shadow_fb);
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/**
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* drm_gem_simple_kms_prepare_shadow_fb - prepares shadow framebuffers
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* @pipe: the simple display pipe
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* @plane_state: the plane state of type struct drm_shadow_plane_state
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*
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* This function implements struct drm_simple_display_funcs.prepare_fb. It
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* maps all buffer objects of the plane's framebuffer into kernel address
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* space and stores them in struct drm_shadow_plane_state.map. The
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* framebuffer will be synchronized as part of the atomic commit.
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*
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* See drm_gem_simple_kms_cleanup_shadow_fb() for cleanup.
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*
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* Returns:
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* 0 on success, or a negative errno code otherwise.
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*/
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int drm_gem_simple_kms_prepare_shadow_fb(struct drm_simple_display_pipe *pipe,
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struct drm_plane_state *plane_state)
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{
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return drm_gem_prepare_shadow_fb(&pipe->plane, plane_state);
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}
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EXPORT_SYMBOL(drm_gem_simple_kms_prepare_shadow_fb);
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/**
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* drm_gem_simple_kms_cleanup_shadow_fb - releases shadow framebuffers
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* @pipe: the simple display pipe
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* @plane_state: the plane state of type struct drm_shadow_plane_state
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*
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* This function implements struct drm_simple_display_funcs.cleanup_fb.
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* This function unmaps all buffer objects of the plane's framebuffer.
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*
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* See drm_gem_simple_kms_prepare_shadow_fb().
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*/
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void drm_gem_simple_kms_cleanup_shadow_fb(struct drm_simple_display_pipe *pipe,
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struct drm_plane_state *plane_state)
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{
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drm_gem_cleanup_shadow_fb(&pipe->plane, plane_state);
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}
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EXPORT_SYMBOL(drm_gem_simple_kms_cleanup_shadow_fb);
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/**
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* drm_gem_simple_kms_reset_shadow_plane - resets a shadow-buffered plane
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* @pipe: the simple display pipe
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*
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* This function implements struct drm_simple_display_funcs.reset_plane
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* for shadow-buffered planes.
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*/
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void drm_gem_simple_kms_reset_shadow_plane(struct drm_simple_display_pipe *pipe)
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{
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drm_gem_reset_shadow_plane(&pipe->plane);
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}
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EXPORT_SYMBOL(drm_gem_simple_kms_reset_shadow_plane);
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/**
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* drm_gem_simple_kms_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
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* @pipe: the simple display pipe
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*
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* This function implements struct drm_simple_display_funcs.duplicate_plane_state
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* for shadow-buffered planes. It does not duplicate existing mappings of the shadow
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* buffers. Mappings are maintained during the atomic commit by the plane's prepare_fb
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* and cleanup_fb helpers.
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*
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* Returns:
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* A pointer to a new plane state on success, or NULL otherwise.
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*/
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struct drm_plane_state *
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drm_gem_simple_kms_duplicate_shadow_plane_state(struct drm_simple_display_pipe *pipe)
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{
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return drm_gem_duplicate_shadow_plane_state(&pipe->plane);
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}
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EXPORT_SYMBOL(drm_gem_simple_kms_duplicate_shadow_plane_state);
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/**
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* drm_gem_simple_kms_destroy_shadow_plane_state - resets shadow-buffered plane state
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* @pipe: the simple display pipe
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* @plane_state: the plane state of type struct drm_shadow_plane_state
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*
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* This function implements struct drm_simple_display_funcs.destroy_plane_state
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* for shadow-buffered planes. It expects that mappings of shadow buffers
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* have been released already.
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*/
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void drm_gem_simple_kms_destroy_shadow_plane_state(struct drm_simple_display_pipe *pipe,
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struct drm_plane_state *plane_state)
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{
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drm_gem_destroy_shadow_plane_state(&pipe->plane, plane_state);
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}
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EXPORT_SYMBOL(drm_gem_simple_kms_destroy_shadow_plane_state);
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