linux-kernel - Re: [Freedreno] [PATCH v2 04/17] drm/msm/dpu: Fix PP_BLK

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Date:   Tue, 25 Apr 2023 22:43:34 +0200
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc:     dri-devel@...ts.freedesktop.org,
        Jordan Crouse <jordan@...micpenguin.net>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        David Airlie <airlied@...il.com>,
        Chandan Uddaraju <chandanu@...eaurora.org>,
        Archit Taneja <architt@...eaurora.org>,
        Robert Foss <rfoss@...nel.org>, Vinod Koul <vkoul@...nel.org>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>,
        Rajesh Yadav <ryadav@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, Adam Skladowski <a39.skl@...il.com>,
        Martin Botka <martin.botka@...ainline.org>,
        ~postmarketos/upstreaming@...ts.sr.ht,
        Jeykumar Sankaran <jsanka@...eaurora.org>,
        Sean Paul <sean@...rly.run>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Loic Poulain <loic.poulain@...aro.org>,
        Jami Kettunen <jami.kettunen@...ainline.org>,
        Bjorn Andersson <andersson@...nel.org>,
        linux-kernel@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Clark <robdclark@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        freedreno@...ts.freedesktop.org,
        Sravanthi Kollukuduru <skolluku@...eaurora.org>
Subject: Re: [Freedreno] [PATCH v2 04/17] drm/msm/dpu: Fix PP_BLK_DIPHER ->
 DITHER typo

On 2023-04-25 09:47:30, Abhinav Kumar wrote:
> 
> 
> On 4/25/2023 9:33 AM, Marijn Suijten wrote:
> > On 2023-04-25 09:18:58, Abhinav Kumar wrote:
> >>
> >>
> >> On 4/24/2023 11:54 PM, Marijn Suijten wrote:
> >>> On 2023-04-24 16:09:45, Abhinav Kumar wrote:
> >>> <snip>
> >>>>>> dither block should be present on many other chipsets too but looks like
> >>>>>> on sm8550 was enabling it. Not sure how it was validated there. But we
> >>>>>> are enabling dither, even other chipsets have this block.
> >>>>>
> >>>>> Correct, they all seem to have it starting at sdm845.  My patch message
> >>>>> seems to lack the word "exclusively" as the PP on sm8550 appears to
> >>>>> exclusively contain a DITHER subblock (unless other blocks are available
> >>>>> that simply aren't supported within this driver yet) and no other
> >>>>> registers.  Hence this aptly named macro exist to emit just the feature
> >>>>> bitflag for that and a .len of zero.
> >>>>>
> >>>>
> >>>> I think after the TE blocks were moved to INTF, dither is the only
> >>>> sub-block for all Ping-Pongs not just in sm8550.
> >>>
> >>> So you are asking / leaving context to make all >= 5.0.0 pingpong blocks
> >>> use this macro with only a single DITHER sblk in PP?
> >>>
> >>> As far as I recall SM8550 is the first SoC to use zero registers in PP,
> >>> which is specifically what this macro takes care of too.  Then, there
> >>> are only a few SoCs downstream still (erroneously?) referencing TE2 as
> >>> the only other sub-blk, those SoCs still use sdm845_pp_sblk_te.
> >>>
> >>
> >> So, what I didnt follow is why should sm8450 use PP_BLK_TE Vs sm8550
> >> should use PP_BLK_DIPHER?
> >>
> >> Atleast for those two, both should be using PP_BLK_DIPHER.
> >>
> >> Thats what I was trying to note here.
> >>
> >> This isnt even right as there is no PP_BLK_TE in sm8450.
> > 
> > SM8450 doesn't use PP_BLK_TE (TE2) anymore since the second patch in
> > this series.  If you think it should use the DITHER (not DIPHER!) macro
> > instead of the regular PP_BLK with a size of 0xd4, we can do that in
> > another patch as that's not strictly related to this series.
> > 
> 
> Yes, thanks for pointing the TE2 was removed in the prev patch of this 
> series for sm8450. I was just focusing too much on this patch.
> 
> And Yes, I think we should use the DIPHER ..... oh sorry .... DITHER ;)
> 
> Yes, it can go as a different series, like I already wrote many times in 
> this.

Thanks, that'd be great.  I wasn't sure at this point what you wanted to
be changed here, after commenting on a typo fix rather than i.e. patch 2
that deals with the TE2 sub-block of PP :)

> But atleast now, someone will remember to do it.
> 
> > Note that that's the only difference between these macros.  The size
> > becomes 0 but the .features mask is the same (SM8450 uses
> > PINGPONG_SM8150_MASK).
> > 
> > These patches are anyway already distracting from my series, but were
> > easier to do in one go as I was touching the PP and INTF catalog blocks
> > regardless.
> > 
> > While at it, perhaps we should check if the version and offset for the
> > DITHER block are correct?  SM8450 uses SDM845 sblk definitions.
> > 
> 
> Yes I already checked. the version and offset of dither are same between 
> sm8450 and sm8550.

Thanks for checking, so then sm8450 is wrong on multiple occasions.
Let's check all other SoCs that use sdm845_pp_sblk whether they should
have used sc7280_pp_sblk instead.

- Marijn