linux-kernel - Re: [PATCH v4 1/5] msm/drm/dsi: Round up DSC hdisplay calculation

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Message-ID: <ecf22436-44f3-8809-1232-e9ae30f3864b@linaro.org>
Date:   Mon, 22 May 2023 22:52:40 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Marijn Suijten <marijn.suijten@...ainline.org>,
        Jessica Zhang <quic_jesszhan@...cinc.com>
Cc:     Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/5] msm/drm/dsi: Round up DSC hdisplay calculation



On 22.05.2023 22:44, Marijn Suijten wrote:
> On 2023-05-22 13:30:20, Jessica Zhang wrote:
>> Currently, when compression is enabled, hdisplay is reduced via integer
>> division. This causes issues for modes where the original hdisplay is
>> not a multiple of 3.
>>
>> To fix this, use DIV_ROUND_UP to divide hdisplay.
>>
>> Reviewed-by: Marijn Suijten <marijn.suijten@...ainline.org>
>> Suggested-by: Marijn Suijten <marijn.suijten@...ainline.org>
> 
> Nit: probably these should go in the opposite order.  And if they're
> all supposed to be chronological, I think it is:
> 
>     Suggested-by:
>     Fixes:
>     Signed-off-by:
>     Reviewed-by:
> 
> But unsure if that's a hard requirement, or even correct at all.
> 
> - Marijn
Or you can rely on b4 to pick that up if it comes from others

Konrad
> 
>> Fixes: 08802f515c3cf ("drm/msm/dsi: Add support for DSC configuration")
>> Signed-off-by: Jessica Zhang <quic_jesszhan@...cinc.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 9223d7ec5a73..18d38b90eb28 100644
>> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
>> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
>> @@ -952,7 +952,7 @@ static void dsi_timing_setup(struct msm_dsi_host *msm_host, bool is_bonded_dsi)
>>  		 * pulse width same
>>  		 */
>>  		h_total -= hdisplay;
>> -		hdisplay = msm_dsc_get_bytes_per_line(msm_host->dsc) / 3;
>> +		hdisplay = DIV_ROUND_UP(msm_dsc_get_bytes_per_line(msm_host->dsc), 3);
>>  		h_total += hdisplay;
>>  		ha_end = ha_start + hdisplay;
>>  	}
>>
>> -- 
>> 2.40.1
>>