linux-kernel - [PATCH AUTOSEL 4.14 6/8] drm/imx: notify drm core before sending event during crtc disable

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Date:   Wed, 10 Jul 2019 11:03:16 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Robert Beckett <bob.beckett@...labora.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Sasha Levin <sashal@...nel.org>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 4.14 6/8] drm/imx: notify drm core before sending event during crtc disable

From: Robert Beckett <bob.beckett@...labora.com>

[ Upstream commit 78c68e8f5cd24bd32ba4ca1cdfb0c30cf0642685 ]

Notify drm core before sending pending events during crtc disable.
This fixes the first event after disable having an old stale timestamp
by having drm_crtc_vblank_off update the timestamp to now.

This was seen while debugging weston log message:
Warning: computed repaint delay is insane: -8212 msec

This occurred due to:
1. driver starts up
2. fbcon comes along and restores fbdev, enabling vblank
3. vblank_disable_fn fires via timer disabling vblank, keeping vblank
seq number and time set at current value
(some time later)
4. weston starts and does a modeset
5. atomic commit disables crtc while it does the modeset
6. ipu_crtc_atomic_disable sends vblank with old seq number and time

Fixes: a474478642d5 ("drm/imx: fix crtc vblank state regression")

Signed-off-by: Robert Beckett <bob.beckett@...labora.com>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/imx/ipuv3-crtc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/imx/ipuv3-crtc.c b/drivers/gpu/drm/imx/ipuv3-crtc.c
index 957fbf8c55eb..7845202d0486 100644
--- a/drivers/gpu/drm/imx/ipuv3-crtc.c
+++ b/drivers/gpu/drm/imx/ipuv3-crtc.c
@@ -99,14 +99,14 @@ static void ipu_crtc_atomic_disable(struct drm_crtc *crtc,
 	ipu_dc_disable(ipu);
 	ipu_prg_disable(ipu);
 
+	drm_crtc_vblank_off(crtc);
+
 	spin_lock_irq(&crtc->dev->event_lock);
 	if (crtc->state->event) {
 		drm_crtc_send_vblank_event(crtc, crtc->state->event);
 		crtc->state->event = NULL;
 	}
 	spin_unlock_irq(&crtc->dev->event_lock);
-
-	drm_crtc_vblank_off(crtc);
 }
 
 static void imx_drm_crtc_reset(struct drm_crtc *crtc)
-- 
2.20.1