linux-kernel - [PATCH v3 2/4] drm/imx: notify drm core before sending event during crtc disable

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Date:   Tue, 25 Jun 2019 18:59:13 +0100
From:   Robert Beckett <bob.beckett@...labora.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Robert Beckett <bob.beckett@...labora.com>
Subject: [PATCH v3 2/4] drm/imx: notify drm core before sending event during crtc disable

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 occured 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>
---
 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 9cc1d678674f..e04d6efff1b5 100644
--- a/drivers/gpu/drm/imx/ipuv3-crtc.c
+++ b/drivers/gpu/drm/imx/ipuv3-crtc.c
@@ -91,14 +91,14 @@ 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)
-- 
2.18.0