drm/vc4: Don't check plane state more than once

We are about to use vc4_plane_mode_set() in the async check path, but
async check can decide that async update is not possible and force the
driver to fallback to a sync update.

All the checks that have been done on the plane state during async check
stay valid, and checking it again is not necessary. Add a ->checked
field to vc4_plane_state, and use it to track the status of the state
(checked or not).

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20181130090254.594-3-boris.brezillon@bootlin.com

2 files changed, 16 insertions, 0 deletions

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index 9ed05fb61eb6..4f87b03f837d 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -370,6 +370,11 @@ struct vc4_plane_state {
 	 * to enable background color fill.
 	 */
 	bool needs_bg_fill;
+
+	/* Mark the dlist as initialized. Useful to avoid initializing it twice
+	 * when async update is not possible.
+	 */
+	bool dlist_initialized;
 };
 
 static inline struct vc4_plane_state *
diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
index 2db021f2d0ae..a4faa5854a85 100644
--- a/drivers/gpu/drm/vc4/vc4_plane.c
+++ b/drivers/gpu/drm/vc4/vc4_plane.c
@@ -154,6 +154,7 @@ static struct drm_plane_state *vc4_plane_duplicate_state(struct drm_plane *plane
 		return NULL;
 
 	memset(&vc4_state->lbm, 0, sizeof(vc4_state->lbm));
+	vc4_state->dlist_initialized = 0;
 
 	__drm_atomic_helper_plane_duplicate_state(plane, &vc4_state->base);
 
@@ -510,6 +511,9 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
 	u32 hvs_format = format->hvs;
 	int ret, i;
 
+	if (vc4_state->dlist_initialized)
+		return 0;
+
 	ret = vc4_plane_setup_clipping_and_scaling(state);
 	if (ret)
 		return ret;
@@ -791,6 +795,13 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
 	vc4_state->needs_bg_fill = fb->format->has_alpha || !covers_screen ||
 				   state->alpha != DRM_BLEND_ALPHA_OPAQUE;
 
+	/* Flag the dlist as initialized to avoid checking it twice in case
+	 * the async update check already called vc4_plane_mode_set() and
+	 * decided to fallback to sync update because async update was not
+	 * possible.
+	 */
+	vc4_state->dlist_initialized = 1;
+
 	return 0;
 }