[PATCH v2 0/3] A DRM API for adaptive sync and variable refresh rate support

[Michel Dänzer]

On 2018-10-11 9:44 p.m., Harry Wentland wrote:
> On 2018-10-03 04:25 AM, Mike Lothian wrote:
>> 
>> I'm curious to know whether this will/could work over PRIME
> 
> I don't see why this shouldn't work over PRIME as long as the
> presenting GPU supports the new variable refresh rate API, but I know
> very little about prime, so maybe someone else can chime in and give
> a better opinion.

It won't work for displays connected to a secondary GPU, because those
aren't hooked up to the Present extension directly.

It can theoretically work with render offloading, if the primary GPU can
scan out directly from the shared pixmap. This is only possible with
current AMD APUs which support scatter/gather scanout (Carrizo and
newer?). One gotcha is that xf86-video-amdgpu currently doesn't allow
flipping between buffers with different tiling parameters (BTW Harry,
does that work with DC?), but that should be easy to fix.


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