linux-kernel - [PATCH 4.9 093/102] drm/imx: notify drm core before sending event during crtc disable

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Date:   Mon,  8 Jul 2019 17:13:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Robert Beckett <bob.beckett@...labora.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Philipp Zabel <p.zabel@...gutronix.de>
Subject: [PATCH 4.9 093/102] drm/imx: notify drm core before sending event during crtc disable

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

commit 78c68e8f5cd24bd32ba4ca1cdfb0c30cf0642685 upstream.

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: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/imx/ipuv3-crtc.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/imx/ipuv3-crtc.c
+++ b/drivers/gpu/drm/imx/ipuv3-crtc.c
@@ -76,14 +76,14 @@ static void ipu_crtc_atomic_disable(stru
 	drm_atomic_helper_disable_planes_on_crtc(old_crtc_state, false);
 	ipu_dc_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)