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

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Message-ID: <CAA8EJpqzj-_fVLXfCrLeTUcwPHE-fb-kNP=SgbVM7U5fQT8p-w@mail.gmail.com>
Date:   Tue, 23 May 2023 01:14:40 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Jessica Zhang <quic_jesszhan@...cinc.com>
Cc:     Marijn Suijten <marijn.suijten@...ainline.org>,
        Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        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 Tue, 23 May 2023 at 00:45, Jessica Zhang <quic_jesszhan@...cinc.com> wrote:
>
>
>
> On 5/22/2023 1:44 PM, 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.
>
> Hi Marijn,
>
> I don't see any explicit documentation on the order of R-b tags. FWIW, I
> see in the git log that S-o-b always goes at the bottom of the commit
> message.
>
> I would prefer the S-o-b to always be at the bottom (as it helps me
> avoid duplicate S-o-b's when doing `git commit -s`), though I can flip
> the order of the R-b and suggested-by tags.

I'd second Jessica here. Consider these tags as a history or a transcript:

I would not vote on the particular order of the Suggested-by/Fixes
tags, I don't think that is important. These come first. Then the
patch goes through different cycles. of reviews, which gain
Reviewed-by tags.

In the same way Link/Patchwork/whatever other tags are added in the
historical order.

By having the submitter's S-o-b at the bottom, the submitter adds the
final signature under everything else being stated/recorded.

Of course, in a more complicated story, there might be other
developers taking part (Co-Developed-By + Signed-off-by), etc.

Note: all described is just my perception and might differ from the
BCP regarding the tags.

>
> Thanks,
>
> Jessica Zhang
>
> >
> > - Marijn
> >
> >> 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
> >>



-- 
With best wishes
Dmitry