diff options
author | Thomas Zimmermann <tzimmermann@suse.de> | 2021-02-22 15:17:56 +0100 |
---|---|---|
committer | Thomas Zimmermann <tzimmermann@suse.de> | 2021-02-23 08:54:22 +0100 |
commit | 820c1707177c6fe96beed7f8cc842a683afbf890 (patch) | |
tree | 7adf720db0e43379919b12d62475c6fc11af415a /drivers/gpu/drm/drm_gem_atomic_helper.c | |
parent | dc739820ff90acccd013f6bb420222978a982791 (diff) | |
download | linux-820c1707177c6fe96beed7f8cc842a683afbf890.tar.bz2 |
drm/gem: Move drm_gem_fb_prepare_fb() to GEM atomic helpers
The function drm_gem_fb_prepare_fb() is a helper for atomic modesetting,
but currently located next to framebuffer helpers. Move it to GEM atomic
helpers, rename it slightly and adopt the drivers. Same for the rsp
simple-pipe helper.
Compile-tested with x86-64, aarch64 and arm. The patch is fairly large,
but there are no functional changes.
v3:
* remove out-comented line in drm_gem_framebuffer_helper.h
(Maxime)
v2:
* rename to drm_gem_plane_helper_prepare_fb() (Daniel)
* add tutorial-style documentation
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210222141756.7864-1-tzimmermann@suse.de
Diffstat (limited to 'drivers/gpu/drm/drm_gem_atomic_helper.c')
-rw-r--r-- | drivers/gpu/drm/drm_gem_atomic_helper.c | 96 |
1 files changed, 92 insertions, 4 deletions
diff --git a/drivers/gpu/drm/drm_gem_atomic_helper.c b/drivers/gpu/drm/drm_gem_atomic_helper.c index fa4eae492b81..a005c5a0ba46 100644 --- a/drivers/gpu/drm/drm_gem_atomic_helper.c +++ b/drivers/gpu/drm/drm_gem_atomic_helper.c @@ -1,6 +1,10 @@ // SPDX-License-Identifier: GPL-2.0-or-later +#include <linux/dma-resv.h> + #include <drm/drm_atomic_state_helper.h> +#include <drm/drm_atomic_uapi.h> +#include <drm/drm_gem.h> #include <drm/drm_gem_atomic_helper.h> #include <drm/drm_gem_framebuffer_helper.h> #include <drm/drm_simple_kms_helper.h> @@ -12,8 +16,33 @@ * * The GEM atomic helpers library implements generic atomic-commit * functions for drivers that use GEM objects. Currently, it provides - * plane state and framebuffer BO mappings for planes with shadow - * buffers. + * synchronization helpers, and plane state and framebuffer BO mappings + * for planes with shadow buffers. + * + * Before scanout, a plane's framebuffer needs to be synchronized with + * possible writers that draw into the framebuffer. All drivers should + * call drm_gem_plane_helper_prepare_fb() from their implementation of + * struct &drm_plane_helper.prepare_fb . It sets the plane's fence from + * the framebuffer so that the DRM core can synchronize access automatically. + * + * drm_gem_plane_helper_prepare_fb() can also be used directly as + * implementation of prepare_fb. For drivers based on + * struct drm_simple_display_pipe, drm_gem_simple_display_pipe_prepare_fb() + * provides equivalent functionality. + * + * .. code-block:: c + * + * #include <drm/drm_gem_atomic_helper.h> + * + * struct drm_plane_helper_funcs driver_plane_helper_funcs = { + * ..., + * . prepare_fb = drm_gem_plane_helper_prepare_fb, + * }; + * + * struct drm_simple_display_pipe_funcs driver_pipe_funcs = { + * ..., + * . prepare_fb = drm_gem_simple_display_pipe_prepare_fb, + * }; * * A driver using a shadow buffer copies the content of the shadow buffers * into the HW's framebuffer memory during an atomic update. This requires @@ -32,7 +61,7 @@ * * .. code-block:: c * - * #include <drm/drm/gem_atomic_helper.h> + * #include <drm/drm_gem_atomic_helper.h> * * struct drm_plane_funcs driver_plane_funcs = { * ..., @@ -88,6 +117,65 @@ */ /* + * Plane Helpers + */ + +/** + * drm_gem_plane_helper_prepare_fb() - Prepare a GEM backed framebuffer + * @plane: Plane + * @state: Plane state the fence will be attached to + * + * This function extracts the exclusive fence from &drm_gem_object.resv and + * attaches it to plane state for the atomic helper to wait on. This is + * necessary to correctly implement implicit synchronization for any buffers + * shared as a struct &dma_buf. This function can be used as the + * &drm_plane_helper_funcs.prepare_fb callback. + * + * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple + * GEM based framebuffer drivers which have their buffers always pinned in + * memory. + * + * See drm_atomic_set_fence_for_plane() for a discussion of implicit and + * explicit fencing in atomic modeset updates. + */ +int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state) +{ + struct drm_gem_object *obj; + struct dma_fence *fence; + + if (!state->fb) + return 0; + + obj = drm_gem_fb_get_obj(state->fb, 0); + fence = dma_resv_get_excl_rcu(obj->resv); + drm_atomic_set_fence_for_plane(state, fence); + + return 0; +} +EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb); + +/** + * drm_gem_simple_display_pipe_prepare_fb - prepare_fb helper for &drm_simple_display_pipe + * @pipe: Simple display pipe + * @plane_state: Plane state + * + * This function uses drm_gem_plane_helper_prepare_fb() to extract the exclusive fence + * from &drm_gem_object.resv and attaches it to plane state for the atomic + * helper to wait on. This is necessary to correctly implement implicit + * synchronization for any buffers shared as a struct &dma_buf. Drivers can use + * this as their &drm_simple_display_pipe_funcs.prepare_fb callback. + * + * See drm_atomic_set_fence_for_plane() for a discussion of implicit and + * explicit fencing in atomic modeset updates. + */ +int drm_gem_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe, + struct drm_plane_state *plane_state) +{ + return drm_gem_plane_helper_prepare_fb(&pipe->plane, plane_state); +} +EXPORT_SYMBOL(drm_gem_simple_display_pipe_prepare_fb); + +/* * Shadow-buffered Planes */ @@ -198,7 +286,7 @@ int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *p if (!fb) return 0; - ret = drm_gem_fb_prepare_fb(plane, plane_state); + ret = drm_gem_plane_helper_prepare_fb(plane, plane_state); if (ret) return ret; |