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drm/gem: Export helpers for shadow-buffered planes

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Export the helpers for shadow-buffered planes. These will be used by
several drivers.

v3:
	* fix documentation typos and formatting (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210209121042.24098-2-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2021-02-09 13:10:41 +01:00
parent 9dd55dfe2e
commit 9dc9067dce
2 changed files with 174 additions and 6 deletions
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148
drivers/gpu/drm/drm_gem_atomic_helper.c
View File

@ -14,13 +14,101 @@
* functions for drivers that use GEM objects. Currently, it provides
* plane state and framebuffer BO mappings for planes with shadow
* buffers.
*
* 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
* a mapping of the shadow buffer into kernel address space. The mappings
* cannot be established by commit-tail functions, such as atomic_update,
* as this would violate locking rules around dma_buf_vmap().
*
* The helpers for shadow-buffered planes establish and release mappings,
* and provide struct drm_shadow_plane_state, which stores the plane's mapping
* for commit-tail functons.
*
* Shadow-buffered planes can easily be enabled by using the provided macros
* %DRM_GEM_SHADOW_PLANE_FUNCS and %DRM_GEM_SHADOW_PLANE_HELPER_FUNCS.
* These macros set up the plane and plane-helper callbacks to point to the
* shadow-buffer helpers.
*
* .. code-block:: c
*
* #include <drm/drm/gem_atomic_helper.h>
*
* struct drm_plane_funcs driver_plane_funcs = {
* ...,
* DRM_GEM_SHADOW_PLANE_FUNCS,
* };
*
* struct drm_plane_helper_funcs driver_plane_helper_funcs = {
* ...,
* DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
* };
*
* In the driver's atomic-update function, shadow-buffer mappings are available
* from the plane state. Use to_drm_shadow_plane_state() to upcast from
* struct drm_plane_state.
*
* .. code-block:: c
*
* void driver_plane_atomic_update(struct drm_plane *plane,
* struct drm_plane_state *old_plane_state)
* {
* struct drm_plane_state *plane_state = plane->state;
* struct drm_shadow_plane_state *shadow_plane_state =
* to_drm_shadow_plane_state(plane_state);
*
* // access shadow buffer via shadow_plane_state->map
* }
*
* A mapping address for each of the framebuffer's buffer object is stored in
* struct &drm_shadow_plane_state.map. The mappings are valid while the state
* is being used.
*
* Drivers that use struct drm_simple_display_pipe can use
* %DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS to initialize the rsp
* callbacks. Access to shadow-buffer mappings is similar to regular
* atomic_update.
*
* .. code-block:: c
*
* struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
* ...,
* DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS,
* };
*
* void driver_pipe_enable(struct drm_simple_display_pipe *pipe,
* struct drm_crtc_state *crtc_state,
* struct drm_plane_state *plane_state)
* {
* struct drm_shadow_plane_state *shadow_plane_state =
* to_drm_shadow_plane_state(plane_state);
*
* // access shadow buffer via shadow_plane_state->map
* }
*/
/*
* Shadow-buffered Planes
*/
static struct drm_plane_state *
/**
* drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
* @plane: the plane
*
* This function implements struct &drm_plane_funcs.atomic_duplicate_state for
* shadow-buffered planes. It assumes the existing state to be of type
* struct drm_shadow_plane_state and it allocates the new state to be of this
* type.
*
* The function does not duplicate existing mappings of the shadow buffers.
* Mappings are maintained during the atomic commit by the plane's prepare_fb
* and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
* for corresponding helpers.
*
* Returns:
* A pointer to a new plane state on success, or NULL otherwise.
*/
struct drm_plane_state *
drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane)
{
struct drm_plane_state *plane_state = plane->state;
@ -36,9 +124,19 @@ drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane)
return &new_shadow_plane_state->base;
}
EXPORT_SYMBOL(drm_gem_duplicate_shadow_plane_state);
static void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
struct drm_plane_state *plane_state)
/**
* drm_gem_destroy_shadow_plane_state - deletes shadow-buffered plane state
* @plane: the plane
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct &drm_plane_funcs.atomic_destroy_state
* for shadow-buffered planes. It expects that mappings of shadow buffers
* have been released already.
*/
void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
struct drm_plane_state *plane_state)
{
struct drm_shadow_plane_state *shadow_plane_state =
to_drm_shadow_plane_state(plane_state);
@ -46,8 +144,18 @@ static void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
__drm_atomic_helper_plane_destroy_state(&shadow_plane_state->base);
kfree(shadow_plane_state);
}
EXPORT_SYMBOL(drm_gem_destroy_shadow_plane_state);
static void drm_gem_reset_shadow_plane(struct drm_plane *plane)
/**
* drm_gem_reset_shadow_plane - resets a shadow-buffered plane
* @plane: the plane
*
* This function implements struct &drm_plane_funcs.reset_plane for
* shadow-buffered planes. It assumes the current plane state to be
* of type struct drm_shadow_plane and it allocates the new state of
* this type.
*/
void drm_gem_reset_shadow_plane(struct drm_plane *plane)
{
struct drm_shadow_plane_state *shadow_plane_state;
@ -61,8 +169,24 @@ static void drm_gem_reset_shadow_plane(struct drm_plane *plane)
return;
__drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);
}
EXPORT_SYMBOL(drm_gem_reset_shadow_plane);
static int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
/**
* drm_gem_prepare_shadow_fb - prepares shadow framebuffers
* @plane: the plane
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct &drm_plane_helper_funcs.prepare_fb. It
* maps all buffer objects of the plane's framebuffer into kernel address
* space and stores them in &struct drm_shadow_plane_state.map. The
* framebuffer will be synchronized as part of the atomic commit.
*
* See drm_gem_cleanup_shadow_fb() for cleanup.
*
* Returns:
* 0 on success, or a negative errno code otherwise.
*/
int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
{
struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
struct drm_framebuffer *fb = plane_state->fb;
@ -100,8 +224,19 @@ err_drm_gem_vunmap:
}
return ret;
}
EXPORT_SYMBOL(drm_gem_prepare_shadow_fb);
static void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
/**
* drm_gem_cleanup_shadow_fb - releases shadow framebuffers
* @plane: the plane
* @plane_state: the plane state of type struct drm_shadow_plane_state
*
* This function implements struct &drm_plane_helper_funcs.cleanup_fb.
* This function unmaps all buffer objects of the plane's framebuffer.
*
* See drm_gem_prepare_shadow_fb() for more inforamtion.
*/
void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
{
struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
struct drm_framebuffer *fb = plane_state->fb;
@ -119,6 +254,7 @@ static void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_
drm_gem_vunmap(obj, &shadow_plane_state->map[i]);
}
}
EXPORT_SYMBOL(drm_gem_cleanup_shadow_fb);
/**
* drm_gem_simple_kms_prepare_shadow_fb - prepares shadow framebuffers

32
include/drm/drm_gem_atomic_helper.h
View File

@ -45,6 +45,38 @@ to_drm_shadow_plane_state(struct drm_plane_state *state)
return container_of(state, struct drm_shadow_plane_state, base);
}
void drm_gem_reset_shadow_plane(struct drm_plane *plane);
struct drm_plane_state *drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane);
void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
struct drm_plane_state *plane_state);
/**
* DRM_GEM_SHADOW_PLANE_FUNCS -
* Initializes struct drm_plane_funcs for shadow-buffered planes
*
* Drivers may use GEM BOs as shadow buffers over the framebuffer memory. This
* macro initializes struct drm_plane_funcs to use the rsp helper functions.
*/
#define DRM_GEM_SHADOW_PLANE_FUNCS \
.reset = drm_gem_reset_shadow_plane, \
.atomic_duplicate_state = drm_gem_duplicate_shadow_plane_state, \
.atomic_destroy_state = drm_gem_destroy_shadow_plane_state
int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state);
void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state);
/**
* DRM_GEM_SHADOW_PLANE_HELPER_FUNCS -
* Initializes struct drm_plane_helper_funcs for shadow-buffered planes
*
* Drivers may use GEM BOs as shadow buffers over the framebuffer memory. This
* macro initializes struct drm_plane_helper_funcs to use the rsp helper
* functions.
*/
#define DRM_GEM_SHADOW_PLANE_HELPER_FUNCS \
.prepare_fb = drm_gem_prepare_shadow_fb, \
.cleanup_fb = drm_gem_cleanup_shadow_fb
int drm_gem_simple_kms_prepare_shadow_fb(struct drm_simple_display_pipe *pipe,
struct drm_plane_state *plane_state);
void drm_gem_simple_kms_cleanup_shadow_fb(struct drm_simple_display_pipe *pipe,