[Mesa-dev] [PATCH] egl/wayland: Set __DRI_IMAGE_USE_SCANOUT for shared buffers

[Michel Dänzer]

On 01.02.2016 12:48, Michel Dänzer wrote:
> On 29.01.2016 21:36, Daniel Stone wrote:
>> On 29 January 2016 at 03:44, Michel Dänzer <michel at daenzer.net> wrote:
>>> It still sounds like significant work (particularly for somebody like me
>>> who isn't very familiar with Wayland details yet). It should be done by
>>> somebody who cares about the difference you're describing. I think it's
>>> unreasonable to expect myself or Axel to do it, especially since you
>>> said on IRC:
>>>
>>>  08:35 #dri-devel: < daniels> mannerov: it makes the flag totally
>>>                    meaningless - s/SCANOUT/NOT_A_FBO/ and i'll ack it
>>>
>>> Which makes little sense to me — even if the SCANOUT flags aren't used
>>> optimally yet, their meaning is quite clear.
>>
>> It's nothing to do with Wayland really.
>>
>> The core problem is that:
>> a) buffer allocation is incompletely described over the wire (AFAICT,
>> tiling is enabled for that buffer, but the combination of RGB format +
>> 0 modifier implies a purely linear format),
> 
> What does "the wire" refer to here, if not the Wayland protocol?
> 
> 
>> which prevents an exacerbating problem from being properly fixed:
>> b) the Gallium gbm implementation does not reject tiled buffers when
>> importing to a display which cannot show tiled buffers
>> and you are proposing a hack:
>> c) pessimise all winsys allocations to the lowest common denominator:
>> avoiding tiling by mandating they be scanout-compatible
> 
> scanout-compatible doesn't imply no tiling, but other than that, sounds
> about right.
> 
> 
>> It works I guess, but until a and b are fixed, performance is going to
>> be suboptimal - again, if there was no performance impact to these
>> allocations, then they would always just happen by default.
> 
> So, which driver(s) in Mesa right now would be affected by this, and how?

Does the lack of response mean there are none?


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