linux-kernel - Re: [RFC PATCH 0/6] drm/msm: DSC Electric Boogaloo for sm8[12]50

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Date:   Thu, 15 Dec 2022 02:52:01 +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>,
        ~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 0/6] drm/msm: DSC Electric Boogaloo for sm8[12]50

On 14/12/2022 21:23, Marijn Suijten wrote:
> On 2022-12-14 20:40:06, Dmitry Baryshkov wrote:
>> On 14/12/2022 01:22, Marijn Suijten wrote:
>>> This preliminary Display Stream Compression support package for
>>> (initially tested on) sm8[12]50 is based on comparing DSC behaviour
>>> between downstream and mainline.  Some new callbacks are added (for
>>> binding blocks on active CTLs), logic bugs are corrected, zeroed struct
>>> members are now assigned proper values, and RM allocation and hw block
>>> retrieval now hand out (or not) DSC blocks without causing null-pointer
>>> dereferences.
>>>
>>> Unfortunately it is not yet enough to get rid of completely corrupted
>>> display output on the boards I tested here:
>>> - Sony Xperia 1 (sm8150), 1644x3840 or 1096x2560 pixels;
>>> - Sony Xperia 5II (sm8250), 1080x2520, at 60 or 120Hz;
>>> - (can include more Xperia boards if desired)
>>>
>>> Both devices use the DUALPIPE_DSCMERGE topology downstream: dual LM, PP
>>> and DSC, but only a single INTF/encoder/DSI-link.
>>>
>>> Hopefully this spawns some community/upstream interest to help rootcause
>>> our corruption issues (after we open a drm/msm report on GitLab for more
>>> appropriate tracking).
>>>
>>> The Sony Xperia XZ3 (sdm845) was fully tested and validated with this
>>> series to not cause any regressions (an one of the math fixes now allows
>>> us to change slice_count in the panel driver, which would corrupt
>>> previously).
>>>
>>> Marijn Suijten (6):
>>>     drm/msm/dpu1: Implement DSC binding to PP block for CTL V1
>>>     drm/msm/dpu1: Add DSC config for sm8150 and sm8250
>>>     drm/msm/dpu1: Wire up DSC mask for active CTL configuration
>>>     drm/msm/dsi: Use DSC slice(s) packet size to compute word count
>>>     drm/msm/dsi: Flip greater-than check for slice_count and
>>>       slice_per_intf
>>>     drm/msm/dpu: Disallow unallocated (DSC) resources to be returned
>>
>> General comment: patches with Fixes ideally should come first. Usually
>> they are picked into -fixes and/or stable kernels. If the Fixes patches
>> are in the middle of the series, one can not be sure that they do not
>> have dependencies on previous patches. If there is one, it should
>> probably be stated clearly to ease work on backporting them.
> 
> Ack, I may have rushed these RFC patches straight off my branches onto
> the lists in hopes of sparking some suggestions on what may still be
> broken or missing to get DSC working on sm[12]50, but will keep this in
> mind for v2 after receiving some more review.
> 
> That said, any suggestions?


 From what I've noticed lately:

- set dsc_version_major/dsc_version_minor
- try using dsc params from 1.2 rater than 1.1 version spec (there is 
small difference there)

-- 
With best wishes
Dmitry