From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Date: Sat, 4 Mar 2017 15:14:47 +0200
Subject: drm: rcar-du: Arm the page flip event after queuing the page flip
Git-commit: 7f53b19cdff78f696b61cd5987dfe1a5d432676b
Patch-mainline: v4.13-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

The page flip event is armed in the atomic begin handler, creating a
race condition with the frame end interrupt that could send the event
before the atomic operation actually completes. To avoid that, arm the
event in the atomic flush handler after queuing the page flip.

This change doesn't fully close the race window, as the frame end
interrupt could be generated before the page flip is committed to
hardware but only handled after the event is armed. However, the race
window is now much smaller.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/rcar-du/rcar_du_crtc.c |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
@@ -581,17 +581,6 @@ static void rcar_du_crtc_atomic_begin(st
 				      struct drm_crtc_state *old_crtc_state)
 {
 	struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
-	struct drm_device *dev = rcrtc->crtc.dev;
-	unsigned long flags;
-
-	if (crtc->state->event) {
-		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
-
-		spin_lock_irqsave(&dev->event_lock, flags);
-		rcrtc->event = crtc->state->event;
-		crtc->state->event = NULL;
-		spin_unlock_irqrestore(&dev->event_lock, flags);
-	}
 
 	if (rcar_du_has(rcrtc->group->dev, RCAR_DU_FEATURE_VSP1_SOURCE))
 		rcar_du_vsp_atomic_begin(rcrtc);
@@ -601,9 +590,20 @@ static void rcar_du_crtc_atomic_flush(st
 				      struct drm_crtc_state *old_crtc_state)
 {
 	struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
+	struct drm_device *dev = rcrtc->crtc.dev;
+	unsigned long flags;
 
 	rcar_du_crtc_update_planes(rcrtc);
 
+	if (crtc->state->event) {
+		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+
+		spin_lock_irqsave(&dev->event_lock, flags);
+		rcrtc->event = crtc->state->event;
+		crtc->state->event = NULL;
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+	}
+
 	if (rcar_du_has(rcrtc->group->dev, RCAR_DU_FEATURE_VSP1_SOURCE))
 		rcar_du_vsp_atomic_flush(rcrtc);
 }