drm/msm/mdp5: Fix wait-for-commit for cmd panels

Before the offending commit in msm_atomic_commit_tail wait_flush was
called once per frame, after the commit was submitted. After it
wait_flush is also called at the beginning to ensure previous
potentially async commits are done.

For cmd panels the source of wait_flush is a ping-pong irq notifying
a completion. The completion needs to be notified with complete_all so
multiple waiting parties (new async committers) can proceed.
Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
Suggested-by: Rob Clark <robdclark@gmail.com>
Fixes: 2d99ced7 ("drm/msm: async commit support")
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/disp/mdp5/mdp5_crtc.c

@@ -1180,7 +1180,7 @@ static void mdp5_crtc_pp_done_irq(struct mdp_irq *irq, uint32_t irqstatus)
 	struct mdp5_crtc *mdp5_crtc = container_of(irq, struct mdp5_crtc,
 								pp_done);
 
-	complete(&mdp5_crtc->pp_completion);
+	complete_all(&mdp5_crtc->pp_completion);
 }
 
 static void mdp5_crtc_wait_for_pp_done(struct drm_crtc *crtc)