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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jeykumar Sankaran <jsanka@codeaurora.org>,
        Sean Paul <seanpaul@chromium.org>,
        Rob Clark <robdclark@gmail.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.20 152/352] drm/msm: dpu: Only check flush register against pending flushes
Date:   Mon, 11 Feb 2019 15:16:19 +0100
Message-Id: <20190211141856.364328528@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 5f79e03b1f7c1b2cf0019ce6365fe5d52629813d ]

There exists a case where a flush of a plane/dma may have been triggered
& started from an async commit. If that plane/dma is subsequently disabled
by the next commit, the flush register will continue to hold the flush
bit for the disabled plane. Since the bit remains active,
pending_kickoff_cnt will never decrement and we'll miss frame_done
events.

This patch limits the check of flush_register to include only those bits
which have been updated with the latest commit.

Changes in v2:
- None

Reviewed-by: Jeykumar Sankaran <jsanka@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
index 84de385a9f62..60f146f02b77 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
@@ -331,7 +331,7 @@ static void dpu_encoder_phys_vid_vblank_irq(void *arg, int irq_idx)
 	if (hw_ctl && hw_ctl->ops.get_flush_register)
 		flush_register = hw_ctl->ops.get_flush_register(hw_ctl);
 
-	if (flush_register == 0)
+	if (!(flush_register & hw_ctl->ops.get_pending_flush(hw_ctl)))
 		new_cnt = atomic_add_unless(&phys_enc->pending_kickoff_cnt,
 				-1, 0);
 	spin_unlock_irqrestore(phys_enc->enc_spinlock, lock_flags);
-- 
2.19.1