drm: rcar-du: Repair vblank for DRM page flips using the VSP

The driver recently switched from handling page flip completion in the
DU vertical blanking handler to the VSP frame end handler to fix a race
condition. This unfortunately resulted in incorrect timestamps in the
vertical blanking events sent to userspace as vertical blanking is now
handled after sending the event.

To fix this we must reverse the order of the two operations. The easiest
way is to handle vertical blanking in the VSP frame end handler before
sending the event. The VSP frame end interrupt occurs approximately 50µs
earlier than the DU frame end interrupt, but this should not cause any
undue harm.

As we need to handle vertical blanking even when page flip completion is
delayed, the VSP driver now needs to call the frame end completion
callback unconditionally, with a new argument to report whether page
flip has completed.

With this new scheme the DU vertical blanking interrupt isn't needed
anymore, so we can stop enabling it.

Fixes: d503a43ac06a ("drm: rcar-du: Register a completion callback with VSP1")
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 10 insertions, 10 deletions

diff --git a/drivers/media/platform/vsp1/vsp1_pipe.c b/drivers/media/platform/vsp1/vsp1_pipe.c
index 9bb961298af2..4f4b732df84b 100644
--- a/drivers/media/platform/vsp1/vsp1_pipe.c
+++ b/drivers/media/platform/vsp1/vsp1_pipe.c
@@ -335,16 +335,12 @@ void vsp1_pipeline_frame_end(struct vsp1_pipeline *pipe)
 	if (pipe == NULL)
 		return;
 
+	/*
+	 * If the DL commit raced with the frame end interrupt, the commit ends
+	 * up being postponed by one frame. @completed represents whether the
+	 * active frame was finished or postponed.
+	 */
 	completed = vsp1_dlm_irq_frame_end(pipe->output->dlm);
-	if (!completed) {
-		/*
-		 * If the DL commit raced with the frame end interrupt, the
-		 * commit ends up being postponed by one frame. Return
-		 * immediately without calling the pipeline's frame end handler
-		 * or incrementing the sequence number.
-		 */
-		return;
-	}
 
 	if (pipe->hgo)
 		vsp1_hgo_frame_end(pipe->hgo);
@@ -352,8 +348,12 @@ void vsp1_pipeline_frame_end(struct vsp1_pipeline *pipe)
 	if (pipe->hgt)
 		vsp1_hgt_frame_end(pipe->hgt);
 
+	/*
+	 * Regardless of frame completion we still need to notify the pipe
+	 * frame_end to account for vblank events.
+	 */
 	if (pipe->frame_end)
-		pipe->frame_end(pipe);
+		pipe->frame_end(pipe, completed);
 
 	pipe->sequence++;
 }