[Freedreno] [RFC PATCH v2 10/13] drm/msm/dpu: add list of supported formats to the DPU caps

[Abhinav Kumar]

On 6/6/2023 3:59 PM, Dmitry Baryshkov wrote:
> On 07/06/2023 01:57, Abhinav Kumar wrote:
>>
>>
>> On 6/6/2023 3:50 PM, Dmitry Baryshkov wrote:
>>> On 07/06/2023 01:47, Abhinav Kumar wrote:
>>>>
>>>>
>>>> On 6/6/2023 2:52 PM, Dmitry Baryshkov wrote:
>>>>> On 07/06/2023 00:47, Abhinav Kumar wrote:
>>>>>>
>>>>>>
>>>>>> On 6/6/2023 2:29 PM, Dmitry Baryshkov wrote:
>>>>>>> On 07/06/2023 00:14, Abhinav Kumar wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 5/24/2023 6:47 PM, Dmitry Baryshkov wrote:
>>>>>>>>> On Thu, 25 May 2023 at 02:16, Abhinav Kumar 
>>>>>>>>> <quic_abhinavk at quicinc.com> wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 3/20/2023 6:18 PM, Dmitry Baryshkov wrote:
>>>>>>>>>>> As we are going to add virtual planes, add the list of 
>>>>>>>>>>> supported formats
>>>>>>>>>>> to the hw catalog entry. It will be used to setup universal 
>>>>>>>>>>> planes, with
>>>>>>>>>>> later selecting a pipe depending on whether the YUV format is 
>>>>>>>>>>> used for
>>>>>>>>>>> the framebuffer.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> If your usage of format_list is going to be internal to 
>>>>>>>>>> dpu_plane.c, I
>>>>>>>>>> can think of another idea for this change.
>>>>>>>>>>
>>>>>>>>>> This essentially translates to if (num_vig >= 1)
>>>>>>>>>>
>>>>>>>>>> If we can just have a small helper to detect that from the 
>>>>>>>>>> catalog can
>>>>>>>>>> we use that instead of adding formats to the dpu caps?
>>>>>>>>>
>>>>>>>>> I'd prefer to be explicit here. The list of supported formats 
>>>>>>>>> might
>>>>>>>>> vary between generations, might it not? Also we don't have a 
>>>>>>>>> case of
>>>>>>>>> the devices not having VIG planes. Even the qcm2290 (which doesn't
>>>>>>>>> have CSC) lists YUV as supported.
>>>>>>>>>
>>>>>>>>
>>>>>>>> the list of formats is tied to the sspps the dpu generation has 
>>>>>>>> and the capabilities of those sspps.
>>>>>>>>
>>>>>>>> qcm2290 is really an interesting case. It has one vig sspp but 
>>>>>>>> no csc block for that vig sspp, hence it cannot support non-RGB 
>>>>>>>> formats.
>>>>>>>>
>>>>>>>> I have confirmed that downstream is incorrect to populate yuv 
>>>>>>>> formats for qcm2290.
>>>>>>>>
>>>>>>>> I still think that having atleast one vig sspp with csc sub-blk 
>>>>>>>> is the right condition to check if we want to decide if the dpu 
>>>>>>>> for that chipset supports yuv formats. Extra csc-blk check to 
>>>>>>>> handle qcm2290.
>>>>>>>>
>>>>>>>> Having a small helper in dpu_plane.c is good enough for that 
>>>>>>>> because with virtual planes, you only need to know "if such a 
>>>>>>>> plane exists and not which plane" and a full catalog change isnt 
>>>>>>>> needed IMO
>>>>>>>
>>>>>>> This goes down to the question: is the list of YUV and non-YUV 
>>>>>>> formats static or not? Do all DPU devices support the same set of 
>>>>>>> YUV and non-YUV formats? If it is static, we might as well drop 
>>>>>>> dpu_sspp_sub_blks::format_list.
>>>>>>>
>>>>>>
>>>>>> I would say yes based on the below reference:
>>>>>>
>>>>>> https://git.codelinaro.org/clo/la/platform/vendor/opensource/display-drivers/-/blob/clo/main/msm/sde/sde_hw_catalog.c#L3858
>>>>>>
>>>>>> We always add the same set of YUV formats for all Vig SSPPs 
>>>>>> irrespective of the chipsets.
>>>>>
>>>>> Well, as your example pointed out, few lines below it starts adding 
>>>>> formats to the list, so the format list is not static and depends 
>>>>> on the generation.
>>>>>
>>>>
>>>> No, the DPU revision checks are there to add P010 UBWC formats on 
>>>> top of the Vig formats.
>>>>
>>>> At the moment, the latest downstream code (code which is not on CLO 
>>>> hence I cannot share) has dropped all that and just checks if P010 
>>>> UBWC is supported for the Vig SSPP and adds all those.
>>>>
>>>> So its still tied to the feature bit whether P010 UBWC is supported 
>>>> in the Vig SSPP and not at the chipset level.
>>>
>>> So, what is the difference? This means that depending on some 
>>> conditions either we can support P010 UBWC or we can not. So the list 
>>> of all suppored formats is not static.
>>>
>>
>> The difference is SSPP level vs chipset level. This patch was made 
>> with chipset level in mind and had to expand the format list for each 
>> chipset.
>>
>> What I am suggesting is its a SSPP level decision. Please note its not 
>> just P010 UBWC but P010 UBWC FOR Vig SSPP.
>>
>> So expanding each chipset's format list is not needed when the 
>> decision can be made just on the basis of the SSPP's feature flag OR 
>> the presence of the csc blk.
> 
> Maybe I misunderstand something. Is P010 UBWC format supported on VIG 
> SSPPs on all generations? The code that you have pointed me suggests 
> that is is not.
> 

No, your understanding is correct that P010 UBWC format is supported 
only on Vig SSPPs of certain generations.

But my point is that, its still a SSPP level decision.

So even if we add P010 UBWC formats later to the list of supported 
formats, what we will do is add that feature bit alone in the Vig SSPP's 
feature mask of that chipset and based on that all the P010 UBWC formats 
for the virtual planes.

But if we follow your approach, we will add another array called 
plane_formats_p010_ubwc and add that to each chipset which will support it.

The only difference in idea is that, based on the SSPP's feature set of 
that chipset we can still determine that Vs adding it to each chipset.

>>
>>>>
>>>>>>
>>>>>>> Note to myself: consider 
>>>>>>> dpu_mdss_cfg::{dma_formats,cursor_formats,vig_formats}. Either 
>>>>>>> migrate dpu_sspp_sub_blks::format_list users to these fields or 
>>>>>>> drop them.
>>>>>>>
>>>>>>
>>>>>> Yes, I agree. There is no need to have format list in the sub_blk 
>>>>>> as for one type of SSPP, it supports the same format across DPU 
>>>>>> generations.
>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> Note: I think at some point we should have a closer look at the 
>>>>>>>>> list
>>>>>>>>> of supported formats and crosscheck that we do not have either
>>>>>>>>> unsupported formats being listed, or missing formats which are not
>>>>>>>>> listed as supported.
>>>>>>>>>
>>>
>