linux-kernel - [PATCH 1/2] drm/msm/dpu: move vblank events to complete

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Message-Id: <20200907170450.370122-1-robdclark@gmail.com>
Date:   Mon,  7 Sep 2020 10:04:47 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     linux-arm-msm@...r.kernel.org, freedreno@...ts.freedesktop.org,
        Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Drew Davenport <ddavenport@...omium.org>,
        Kalyan Thota <kalyan_t@...eaurora.org>,
        Hongbo Yao <yaohongbo@...wei.com>, Bernard <bernard@...o.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/2] drm/msm/dpu: move vblank events to complete_commit()

From: Rob Clark <robdclark@...omium.org>

We could get a vblank event racing with the current atomic commit,
resulting in sending the pageflip event to userspace early, causing
tearing.  On the other hand, complete_commit() ensures that the
pending flush is complete.

Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index c2729f71e2fa..89c0245b5de5 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -297,7 +297,6 @@ void dpu_crtc_vblank_callback(struct drm_crtc *crtc)
 		dpu_crtc->vblank_cb_time = ktime_get();
 	else
 		dpu_crtc->vblank_cb_count++;
-	_dpu_crtc_complete_flip(crtc);
 	drm_crtc_handle_vblank(crtc);
 	trace_dpu_crtc_vblank_cb(DRMID(crtc));
 }
@@ -402,6 +401,7 @@ static void dpu_crtc_frame_event_cb(void *data, u32 event)
 void dpu_crtc_complete_commit(struct drm_crtc *crtc)
 {
 	trace_dpu_crtc_complete_commit(DRMID(crtc));
+	_dpu_crtc_complete_flip(crtc);
 }
 
 static void _dpu_crtc_setup_lm_bounds(struct drm_crtc *crtc,
-- 
2.26.2