[Mesa-dev] [PATCH 1/3] vl/dri3: use external texture as back buffers(v4)

[Michel Dänzer]

On 10/01/17 09:07 PM, Andy Furniss wrote:
> Andy Furniss wrote:
> 
>> Though recent testing shows this is not true with DAL/DC on 3.7 -
>> todo test DC on new drm-next branch.
> 
> todo done, DC for some reason on both amd-staging-4.7 and
> amd-staging-drm-next is "slower" = the tear region is 2 to 3 times
> larger than non DC kernel with powerplay auto. With high it is smaller
> but still present.

This particular issue is because DC uses the GPU's VUPDATE interrupt
instead of the VBLANK interrupt to drive the DRM vblank machinery. The
result is that userspace is only notified of a vertical blank period
when it's already over, so it doesn't get a chance to do anything inside
the vertical blank period.


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