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

[Harry Wentland]

On 2017-01-11 12:50 AM, Michel Dänzer wrote:
> 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.
>
>

Adding Tony for comment on why DC behaves the way it does.

Harry