Date:   Tue, 25 Apr 2023 14:55:56 -0700
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     Marijn Suijten <marijn.suijten@...ainline.org>
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 4/25/2023 2:53 PM, Marijn Suijten wrote:
> On 2023-04-25 14:37:21, Abhinav Kumar wrote:
>>
>>
>> On 4/25/2023 1:43 PM, Marijn Suijten wrote:
>>> 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 :)
>>>
>>
>> The reason I commented on this patch is because all the discussion so
>> far was surrounding the PP_BLK_DITHER macro which was being touched in
>> this patch.
>>
>> So even now, we found out about sm8450 and sm8550 because of the
>> question that why sm8550 alone should use PP_BLK_DITHER and not sm8450.
>>
>> This patch led to all the discussion about PP_BLK_DITHER.
>>
>> Even though it was just a typo fix patch, it uncovered deeper issues in
>> catalog about why PP_BLK_DITHER wasnt used more often.
> 
> Indeed: the initial question was for the dither _block_ which is enabled
> on every other platform, just through the original macros which do more
> than exclusively enabling the dither block.
> 
>>>> But atleast now, someone will remember to do it.
> 
> I'll see whether I can include these fixes before sending v3 (got all
> the other changes in and am all-ready to send it): is there any other
> SoC you're seeing this issue on?
> 

Thats alright, you can have it in a separate series not v3 of this one.

I am picking up the fixes from this one now.

I will update the other SOCs on IRC or even better i will take up this 
cleanup.

> - Marijn
> 
>>>>> 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

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