drm/atomic-helper: Add {begin,end}_fb_access to plane helpers

Add {begin,end}_fb_access helpers to run at the beginning and end of
an atomic commit. The begin_fb_access helper acquires resources that
are necessary to perform the atomic commit. It it similar to prepare_fb,
except that the resources are to be released at the end of the commit.
Resources acquired by prepare_fb are held until after the next pageflip.

The end_fb_access helper performs the corresponding resource cleanup.
Atomic helpers call it with the new plane state. This is different from
cleanup_fb, which releases resources of the old plane state.

v2:
	* fix typos in commit message (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221025101737.8874-2-tzimmermann@suse.de

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
index 31233c6ae3c4..3ef420ec4534 100644
--- a/drivers/gpu/drm/drm_simple_kms_helper.c
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -285,6 +285,30 @@ static void drm_simple_kms_plane_cleanup_fb(struct drm_plane *plane,
 	pipe->funcs->cleanup_fb(pipe, state);
 }
 
+static int drm_simple_kms_plane_begin_fb_access(struct drm_plane *plane,
+						struct drm_plane_state *new_plane_state)
+{
+	struct drm_simple_display_pipe *pipe;
+
+	pipe = container_of(plane, struct drm_simple_display_pipe, plane);
+	if (!pipe->funcs || !pipe->funcs->begin_fb_access)
+		return 0;
+
+	return pipe->funcs->begin_fb_access(pipe, new_plane_state);
+}
+
+static void drm_simple_kms_plane_end_fb_access(struct drm_plane *plane,
+					       struct drm_plane_state *new_plane_state)
+{
+	struct drm_simple_display_pipe *pipe;
+
+	pipe = container_of(plane, struct drm_simple_display_pipe, plane);
+	if (!pipe->funcs || !pipe->funcs->end_fb_access)
+		return;
+
+	pipe->funcs->end_fb_access(pipe, new_plane_state);
+}
+
 static bool drm_simple_kms_format_mod_supported(struct drm_plane *plane,
 						uint32_t format,
 						uint64_t modifier)
@@ -295,6 +319,8 @@ static bool drm_simple_kms_format_mod_supported(struct drm_plane *plane,
 static const struct drm_plane_helper_funcs drm_simple_kms_plane_helper_funcs = {
 	.prepare_fb = drm_simple_kms_plane_prepare_fb,
 	.cleanup_fb = drm_simple_kms_plane_cleanup_fb,
+	.begin_fb_access = drm_simple_kms_plane_begin_fb_access,
+	.end_fb_access = drm_simple_kms_plane_end_fb_access,
 	.atomic_check = drm_simple_kms_plane_atomic_check,
 	.atomic_update = drm_simple_kms_plane_atomic_update,
 };