linux-kernel - Re: [PATCH 3/4] drm/msm/dpu: Add has_data_compress to dpu

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Date:   Thu, 4 May 2023 01:03:35 +0200
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     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>,
        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 3/4] drm/msm/dpu: Add has_data_compress to dpu_caps

Hi Jessica,

On 2023-05-03 12:03:40, Jessica Zhang wrote:
> 
> 
> On 5/3/2023 12:07 AM, Marijn Suijten wrote:
> > On 2023-05-02 18:19:14, Jessica Zhang wrote:
> >> Add data_compress feature to DPU HW catalog.
> >>
> >> In DPU 7.x and later, there is a DATA_COMPRESS register that must be set
> >> within the DPU INTF block for DSC to work.
> >>
> >> As core_rev (and related macros) was removed from the dpu_kms struct, the
> >> most straightforward way to indicate the presence of this register would be
> >> to have a flag in dpu_caps.
> > 
> > This is a very generic name to have in the global dpu_caps for a very
> > specific register on the INTF block since DPU >= 7.0.0, and I doubt any
> > new catalog contributor will know how to fill this field.  After all,
> > DPU < 7.0.0 also has DCE but it is controlled via the PINGPONG block.
> > 
> > Instead, how about having it as a DPU_INTF_DATA_COMPRESS (or similar)
> > feature flag on the INTF block?  We do the same for other (register
> > related) features on the INTF block, and you did the same to disable DSC
> > callbacks on PP in [1].

(Note: I said "you" but meant Kuogee)

> Hi Marijn,
> 
> Sounds good.
> 
> > 
> > In fact it seems that the DSC/DCE (enablement) registers have been moved
> > from PINGPONG to INTF in DPU 7.0.0.  Can you clarify in the patch
> > message for v2 that this is the case, and do the same in the linked
> > PINGPONG patch?  Perhaps these patches should be part of the same series
> > as they do not seem DSI-specific.
> 
> Will make a note of the PP to INTF change in the commit message.

Thanks.

> I would prefer to keep this patch in this series is because it is needed 
> for DSI over command mode to work and the subsequent patch is 
> specifically for command mode.

That is fine, but do mention this in the commit message if it is
relevant here.  Otherwise only mention it as part of patch 4/4.

- Marijn