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

[Michel Dänzer]

On 28/07/17 04:14 PM, Daniel Stone wrote:
> On 26 July 2017 at 07:21, Michel Dänzer <michel at daenzer.net> wrote:
>> On 26/07/17 10:48 AM, Michel Dänzer wrote:
>>> On 26/07/17 06:20 AM, Eric Anholt wrote:
>>>> Daniel Stone <daniels at collabora.com> writes:
>>>>> +   The exact configuration of the buffer is specified by 'format',
>>>>> +   a DRM FourCC format token as defined in that project's
>>>>> +   drm_fourcc.h header, in combination with the modifier.
>>>>
>>>> Should we be specifying how the depth of the Pixmap is determined from
>>>> the fourcc?  Should we be specifying if X11 rendering works on various
>>>> fourccs, and between pixmaps of different fourccs?  It's not clear to me
>>>> what glamor would need to be able to do with these pixmaps (can I
>>>> CopyArea between XRGB888 and BGRX8888?  What does that even mean?)
>>>
>>> X11 pixmaps provide storage for n bits per pixel, where n is the pixmap
>>> depth. CopyArea between pixmaps just copies the bits in the source to
>>> the destination verbatim. Note that this is only possible if both
>>> pixmaps have the same depth.
>>
>> This raises a question about multi-plane (e.g. YUV) formats, where
>> different planes may have different resolutions. Is this functionality
>> intended to be used for such formats? If so, how are X11 drawing
>> operations to/from pixmaps created from such formats envisioned to work?
> 
> Honestly, I wasn't planning on attacking YUV right now, especially
> render-to-YUV. Not least since that brings the complexity of wide vs.
> narrow range and selection of primaries into play. I wouldn't expect
> any server to advertise that as a supported format; one which would
> had better have that figured out ...
> 
> Should we perhaps insert text specifically enforcing only RGB formats?

Probably, assuming there should be any reference to formats at all.


BTW, what's the purpose of supporting four buffers per pixmap, if not
for multi-plane formats?


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer