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Message-ID: <ca33cb5d-363d-dddd-4ad9-62f8a2d87bb1@linaro.org>
Date: Wed, 14 Dec 2022 20:52:54 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Marijn Suijten <marijn.suijten@...ainline.org>,
phone-devel@...r.kernel.org, Rob Clark <robdclark@...il.com>,
Abhinav Kumar <quic_abhinavk@...cinc.com>,
Vinod Koul <vkoul@...nel.org>
Cc: ~postmarketos/upstreaming@...ts.sr.ht,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@...ainline.org>,
Konrad Dybcio <konrad.dybcio@...ainline.org>,
Martin Botka <martin.botka@...ainline.org>,
Jami Kettunen <jami.kettunen@...ainline.org>,
Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Stephen Boyd <swboyd@...omium.org>,
Bjorn Andersson <andersson@...nel.org>,
Jessica Zhang <quic_jesszhan@...cinc.com>,
Ville Syrjälä <ville.syrjala@...ux.intel.com>,
Kuogee Hsieh <quic_khsieh@...cinc.com>,
Jani Nikula <jani.nikula@...el.com>,
sunliming <sunliming@...inos.cn>,
Sam Ravnborg <sam@...nborg.org>,
Haowen Bai <baihaowen@...zu.com>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
Loic Poulain <loic.poulain@...aro.org>,
Vinod Polimera <quic_vpolimer@...cinc.com>,
Douglas Anderson <dianders@...omium.org>,
Vladimir Lypak <vladimir.lypak@...il.com>,
linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 4/6] drm/msm/dsi: Use DSC slice(s) packet size to
compute word count
On 14/12/2022 01:22, Marijn Suijten wrote:
> According to downstream the value to use for WORD_COUNT is
> bytes_per_pkt, which denotes the number of bytes in a packet based on
> how many slices have been configured by the panel driver times the
> width of a slice times the number of bytes per pixel.
>
> The DSC panels seen thus far use one byte per pixel, only one slice
> per packet, and a slice width of half the panel width leading to the
> desired bytes_per_pkt+1 value to be equal to hdisplay/2+1. This however
> isn't the case anymore for panels that configure two slices per packet,
> where the value should now be hdisplay+1.
>
> Note that the aforementioned panel (on a Sony Xperia XZ3, sdm845) with
> slice_count=1 has also been tested to successfully accept slice_count=2,
> which would have shown corrupted output previously.
>
> Fixes: 08802f515c3c ("drm/msm/dsi: Add support for DSC configuration")
> Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
> ---
> drivers/gpu/drm/msm/dsi/dsi_host.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
--
With best wishes
Dmitry
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