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, 31 insertions, 3 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 1a586b3c454b..d579fd8f7cb8 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2536,7 +2536,7 @@ int drm_atomic_helper_prepare_planes(struct drm_device *dev,
 		if (funcs->prepare_fb) {
 			ret = funcs->prepare_fb(plane, new_plane_state);
 			if (ret)
-				goto fail;
+				goto fail_prepare_fb;
 		} else {
 			WARN_ON_ONCE(funcs->cleanup_fb);
 
@@ -2545,13 +2545,34 @@ int drm_atomic_helper_prepare_planes(struct drm_device *dev,
 
 			ret = drm_gem_plane_helper_prepare_fb(plane, new_plane_state);
 			if (ret)
-				goto fail;
+				goto fail_prepare_fb;
+		}
+	}
+
+	for_each_new_plane_in_state(state, plane, new_plane_state, i) {
+		const struct drm_plane_helper_funcs *funcs = plane->helper_private;
+
+		if (funcs->begin_fb_access) {
+			ret = funcs->begin_fb_access(plane, new_plane_state);
+			if (ret)
+				goto fail_begin_fb_access;
 		}
 	}
 
 	return 0;
 
-fail:
+fail_begin_fb_access:
+	for_each_new_plane_in_state(state, plane, new_plane_state, j) {
+		const struct drm_plane_helper_funcs *funcs = plane->helper_private;
+
+		if (j >= i)
+			continue;
+
+		if (funcs->end_fb_access)
+			funcs->end_fb_access(plane, new_plane_state);
+	}
+	i = j; /* set i to upper limit to cleanup all planes */
+fail_prepare_fb:
 	for_each_new_plane_in_state(state, plane, new_plane_state, j) {
 		const struct drm_plane_helper_funcs *funcs;
 
@@ -2828,6 +2849,13 @@ void drm_atomic_helper_cleanup_planes(struct drm_device *dev,
 	int i;
 
 	for_each_oldnew_plane_in_state(old_state, plane, old_plane_state, new_plane_state, i) {
+		const struct drm_plane_helper_funcs *funcs = plane->helper_private;
+
+		if (funcs->end_fb_access)
+			funcs->end_fb_access(plane, new_plane_state);
+	}
+
+	for_each_oldnew_plane_in_state(old_state, plane, old_plane_state, new_plane_state, i) {
 		const struct drm_plane_helper_funcs *funcs;
 		struct drm_plane_state *plane_state;