[Mesa-dev] [PATCH dri3proto v2] Add modifier/multi-plane requests, bump to v1.1

[Nicolai Hähnle]

On 27.07.2017 03:14, Michel Dänzer wrote:
> On 26/07/17 09:15 PM, Nicolai Hähnle wrote:
>> On 26.07.2017 08:29, Michel Dänzer wrote:
>>> On 25/07/17 05:28 PM, Nicolai Hähnle wrote:
>>>> On 22.07.2017 14:00, Daniel Stone wrote:
>>>>>
>>>>> Given that, I'm fairly inclined to punt those until we have the grand
>>>>> glorious allocator, rather than trying to add it to EGL/GBM
>>>>> separately. The modifiers stuff was a fairly obvious augmentation -
>>>>> EGL already had no-modifier format import but no query as to which
>>>>> formats it would accept, and modifiers are a logical extension of
>>>>> format - but adding the other restrictions is a bigger step forward.
>>>>
>>>> Perhaps a third option would be to encode the required pitch_in_bytes
>>>> alignment as part of the modifier?
>>>>
>>>> So DRI3GetSupportedModifiers would return DRM_FORMAT_MOD_LINEAR_256B
>>>> when the display GPU is a Raven Ridge.
>>>>
>>>> More generally, we could say that fourcc_mod_code(NONE, k) means that
>>>> the pitch_in_bytes has to be a multiple of 2**k for e.g. k <= 31. Or if
>>>> you prefer, we could have a stride requirement in elements or pixels
>>>> instead of bytes.
>>>
>>> Interesting idea. FWIW, I suspect we'd need to support specifying the
>>> requirement in both bytes or pixels, since one or the other alone may
>>> not be sufficient to describe the constraints of all hardware.
>>
>>  From what I've seen, modifiers are always specified together with one
>> specific format, so the bytes-per-pixel are always known, so I don't
>> think we need both.
> 
> The proposal adds two DRI3 extension requests for querying the list of
> supported formats and modifiers, respectively. This suggests that the
> supported formats and modifiers can be freely combined.

Which are these? I only saw DRI3GetSupportedModifiers, which takes both 
a window and a format argument.

Cheers,
Nicolai
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