linux-kernel - Re: [PATCH] drm/msm/dpu: Disable dither in phys encoder cleanup

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Message-ID: <3606b749-a476-4c52-9f8b-5e4b465c5e79@quicinc.com>
Date: Wed, 12 Feb 2025 12:23:29 -0800
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Jessica Zhang <quic_jesszhan@...cinc.com>,
        Rob Clark
	<robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        "Sean
 Paul" <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        "David Airlie" <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
CC: <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/msm/dpu: Disable dither in phys encoder cleanup



On 2/11/2025 7:59 PM, Jessica Zhang wrote:
> Disable pingpong dither in dpu_encoder_helper_phys_cleanup().
> 
> This avoids the issue where an encoder unknowingly uses dither after
> reserving a pingpong block that was previously bound to an encoder that
> had enabled dither.
> 
> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Closes: https://lore.kernel.org/all/jr7zbj5w7iq4apg3gofuvcwf4r2swzqjk7sshwcdjll4mn6ctt@l2n3qfpujg3q/
> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.com>
> ---
> This was tested on SC7180 Trogdor by pulling in the concurrent writeback
> series [1] and running the IGT kms_writeback@...teback_check_output
> subtest.
> 
> [1] https://patchwork.freedesktop.org/series/144083/
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 3 +++
>   1 file changed, 3 insertions(+)
> 

Was an extremely tricky issue to debug.

Glad this one is resolved,

Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>