linux-kernel - [PATCH AUTOSEL for 4.9 116/293] drm/vc4: Send a VBLANK event when disabling a CRTC

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Date:   Mon, 9 Apr 2018 00:24:23 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 116/293] drm/vc4: Send a VBLANK event when
 disabling a CRTC

From: Boris Brezillon <boris.brezillon@...e-electrons.com>

[ Upstream commit edeb729f7929d1372ab426a7f56fd0b337ba5751 ]

VBLANK events are missed when the CRTC is being disabled because the
driver does not wait till the end of the frame before stopping the
HVS and PV blocks. In this case, we should explicitly issue a VBLANK
event if there's one waiting.

Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
Reviewed-by: Eric Anholt <eric@...olt.net>
Link: http://patchwork.freedesktop.org/patch/msgid/1497601833-24588-1-git-send-email-boris.brezillon@free-electrons.com
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/gpu/drm/vc4/vc4_crtc.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
index c7e6c9839c9a..474b9372fea6 100644
--- a/drivers/gpu/drm/vc4/vc4_crtc.c
+++ b/drivers/gpu/drm/vc4/vc4_crtc.c
@@ -522,6 +522,19 @@ static void vc4_crtc_disable(struct drm_crtc *crtc)
 	WARN_ON_ONCE((HVS_READ(SCALER_DISPSTATX(chan)) &
 		      (SCALER_DISPSTATX_FULL | SCALER_DISPSTATX_EMPTY)) !=
 		     SCALER_DISPSTATX_EMPTY);
+
+	/*
+	 * Make sure we issue a vblank event after disabling the CRTC if
+	 * someone was waiting it.
+	 */
+	if (crtc->state->event) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&dev->event_lock, flags);
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		crtc->state->event = NULL;
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+	}
 }
 
 static void vc4_crtc_enable(struct drm_crtc *crtc)
-- 
2.15.1