linux-kernel - Re: [PATCH v2 3/4] drm/msm/dpu: Add DPU_INTF_DATA

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Date:   Tue, 9 May 2023 03:48:40 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Jessica Zhang <quic_jesszhan@...cinc.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>
Cc:     Rob Clark <robdclark@...il.com>, 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 v2 3/4] drm/msm/dpu: Add DPU_INTF_DATA_COMPRESS feature
 flag

On 09/05/2023 03:28, Abhinav Kumar wrote:
> 
> 
> On 5/8/2023 4:08 PM, Dmitry Baryshkov wrote:
>> On 09/05/2023 00:46, Jessica Zhang wrote:
>>>
>>>
>>> On 5/7/2023 9:00 AM, Marijn Suijten wrote:
>>>> On 2023-05-05 14:23:50, Jessica Zhang wrote:
>>>>> Add DATA_COMPRESS feature flag to DPU INTF block.
>>>>>
>>>>> In DPU 7.x and later, DSC/DCE enablement registers have been moved 
>>>>> from
>>>>> PINGPONG to INTF.
>>>>>
>>>>> 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 feature flag.
>>>>
>>>> Irrelevant.  Even though core_rev was still in mainline until recently,
>>>> we always hardcoded the features in the catalog and only used core_rev
>>>> to select a dpu_mdss_cfg catalog entry.  There is no "if version >= X
>>>> then enable feature Y" logic, this manually-enabled feature flag is the
>>>> only, correct way to do it.
>>>
>>> Hi Marijn,
>>>
>>> Understood. FWIW, if we do find more register bit-level differences 
>>> between HW versions in the future, it might make more sense to keep 
>>> the HW catalog small and bring core_rev back, rather than keep adding 
>>> these kinds of small differences to caps.
>>
>> Let's see how it goes. Abhinav suggested that there might be feature 
>> differences inside the DPU generations (and even inside the single DPU 
>> major/minor combo). So I'm not sure what core_rev will bring us.
>>
> 
> It allows us to have if MDSS_REV() checks which are convenient for some 
> calculations / bit programming which we dont want to expose in the 
> catalog as they cannot be classified as a hw cap as such or atleast we 
> dont want them to be classified as such.
> 
>> Let's land the platforms which are ready (or if there is anything 
>> close to be submitted). I'll post the next proposal for the catalog 
>> cleanups close to -rc4, when the dust settles then we can have one or 
>> two weaks for the discussion and polishing.
>>
>> I'd like to consider:
>> - inlining foo_BLK macros, if that makes adding new features easier
>> - reformat of clk_ctrls
>> - maybe reintroduction of per-generation feature masks instead of 
>> keeping them named after the random SoC
>> - maybe a rework of mdss_irqs / INTFn_INTR. We already have this info 
>> in hw catalog.
>>
>> Comments are appreciated.
>>
> 
> I would say, lets wait for DSC to settle. Atleast the parts already on 
> the list. Continuous rebase of features already on the list is becoming 
> time consuming because of overlapping catalog reworks.

As I wrote, -rc4. Until that time, I'd expect DSC to be settled and 
accepted.

-- 
With best wishes
Dmitry