linux-kernel - Re: [PATCH 0/2] DPU1 GC1.8 wiring-up

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Message-ID: <47d32e5e-49ad-3ffa-2862-26b78c9c6a98@linaro.org>
Date:   Thu, 20 Apr 2023 23:09:13 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] DPU1 GC1.8 wiring-up

On 20/04/2023 22:53, Abhinav Kumar wrote:
> 
> 
> On 4/20/2023 12:51 PM, Dmitry Baryshkov wrote:
>> On 20/04/2023 22:47, Abhinav Kumar wrote:
>>>
>>>
>>> On 4/20/2023 11:01 AM, Dmitry Baryshkov wrote:
>>>> On 20/04/2023 04:36, Konrad Dybcio wrote:
>>>>>
>>>>>
>>>>> On 20.04.2023 03:28, Abhinav Kumar wrote:
>>>>>>
>>>>>>
>>>>>> On 4/19/2023 6:26 PM, Konrad Dybcio wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 20.04.2023 03:25, Dmitry Baryshkov wrote:
>>>>>>>> On 20/04/2023 04:14, Konrad Dybcio wrote:
>>>>>>>>> Almost all SoCs from SDM845 to SM8550 inclusive feature a GC1.8
>>>>>>>>> dspp sub-block in addition to PCCv4. The other block differ a bit
>>>>>>>>> more, but none of them are supported upstream.
>>>>>>>>>
>>>>>>>>> This series adds configures the GCv1.8 on all the relevant SoCs.
>>>>>>>>
>>>>>>>> Does this mean that we will see gamma_lut support soon?
>>>>>>> No promises, my plate is not even full, it's beyond overflowing! :P
>>>>>>>
>>>>>>> Konrad
>>>>>>
>>>>>> So I think I wrote about this before during the catalog 
>>>>>> rework/fixes that the gc registers are not written to / programmed.
>>>>>>
>>>>>> If thats not done, is there any benefit to this series?
>>>>> Completeness and preparation for the code itself, if nothing else?
>>>>
>>>> The usual problem is that if something is not put to use, it quickly 
>>>> rots or becomes misused for newer platforms. We have seen this with 
>>>> the some of DPU features.
>>>>
>>>> In case of GC (and the freshly defined DPU_DSPP_IGC, but not used) 
>>>> we have three options:
>>>> - drop the unused GC from msm8998_sblk.
>>>> - keep things as is, single unused GC entry
>>>> - fill all the sblk with the correct information in hope that it 
>>>> stays correct
>>>>
>>>> Each of these options has its own drawbacks. I have slight bias 
>>>> towards the last option, to have the information in place (as long 
>>>> as it is accurate).
>>>>
>>>
>>> My vote is for (1) . Today, GC is unused and from the discussion 
>>> here, there is no concrete plan to add it. If we keep extending an 
>>> unused bitmask for all the chipsets including the ones which will get 
>>> added in the future in the hope that someday the feature comes, it 
>>> doesnt sound like a good idea.
>>>
>>> I would rather do (1), if someone has time.
>>
>> Agree, this was the second item on my preference list. Could you 
>> please send this oneliner?
>>
> 
> Sure, i will send this by tomorrow, but its not a oneliner. Need to get 
> rid of below too:
> 
> 470 struct dpu_dspp_sub_blks {
> 471     struct dpu_pp_blk gc;

Agree.

> 
>>> OR lets stay at (2) till someone does (1).
>>>
>>> When someone implements GC, we can re-use this patch and that time 
>>> keep konrad's author rights or co-developed by.
>>>
>>>
>>

-- 
With best wishes
Dmitry