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Message-ID: <9a1db357-9cd4-1217-83b0-c146e7e29233@quicinc.com>
Date:   Fri, 16 Dec 2022 15:01:57 -0800
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Subject: Re: [RFC PATCH 4/6] drm/msm/dsi: Use DSC slice(s) packet size to
 compute word count
Content-Language: en-US
To:     Marijn Suijten <marijn.suijten@somainline.org>,
        <phone-devel@vger.kernel.org>, Rob Clark <robdclark@gmail.com>,
        "Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>,
        Vinod Koul <vkoul@kernel.org>
CC:     <~postmarketos/upstreaming@lists.sr.ht>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@somainline.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>,
        Martin Botka <martin.botka@somainline.org>,
        Jami Kettunen <jami.kettunen@somainline.org>,
        Sean Paul <sean@poorly.run>, David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        "Stephen Boyd" <swboyd@chromium.org>,
        Bjorn Andersson <andersson@kernel.org>,
        "Jessica Zhang" <quic_jesszhan@quicinc.com>,
        =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= <ville.syrjala@linux.intel.com>,
        Kuogee Hsieh <quic_khsieh@quicinc.com>,
        "Jani Nikula" <jani.nikula@intel.com>,
        sunliming <sunliming@kylinos.cn>,
        "Sam Ravnborg" <sam@ravnborg.org>,
        Haowen Bai <baihaowen@meizu.com>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Loic Poulain <loic.poulain@linaro.org>,
        "Vinod Polimera" <quic_vpolimer@quicinc.com>,
        Douglas Anderson <dianders@chromium.org>,
        Vladimir Lypak <vladimir.lypak@gmail.com>,
        <linux-arm-msm@vger.kernel.org>, <dri-devel@lists.freedesktop.org>,
        <freedreno@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
References: <20221213232207.113607-1-marijn.suijten@somainline.org>
 <20221213232207.113607-5-marijn.suijten@somainline.org>
From:   Abhinav Kumar <quic_abhinavk@quicinc.com>
In-Reply-To: <20221213232207.113607-5-marijn.suijten@somainline.org>
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On 12/13/2022 3:22 PM, 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@somainline.org>

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
> ---
>   drivers/gpu/drm/msm/dsi/dsi_host.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index b83cf70b1adb..0686c35a6fd4 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -989,7 +989,7 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>   		if (!msm_host->dsc)
>   			wc = hdisplay * dsi_get_bpp(msm_host->format) / 8 + 1;
>   		else
> -			wc = mode->hdisplay / 2 + 1;
> +			wc = msm_host->dsc->slice_chunk_size * msm_host->dsc->slice_count + 1;
>   
>   		dsi_write(msm_host, REG_DSI_CMD_MDP_STREAM0_CTRL,
>   			DSI_CMD_MDP_STREAM0_CTRL_WORD_COUNT(wc) |