[Mesa-dev] [PATCH] [AMD] dri3: Add adaptive_sync_enable driconf option

Nicolai Hähnle nhaehnle at gmail.com
Tue Oct 17 11:18:21 UTC 2017

On 17.10.2017 12:41, Michel Dänzer wrote:
> On 17/10/17 12:29 PM, Nicolai Hähnle wrote:
>> On 17.10.2017 12:07, Michel Dänzer wrote:
>>> On 17/10/17 11:33 AM, Nicolai Hähnle wrote:
>>>> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>>>> When enabled, this will request FreeSync via the hybrid amdgpu DDX's
>>>> AMDGPU X11 protocol extension.
>>>> Due to limitations in the DDX this will only work for applications
>>>> that cover the entire X screen (which is important to keep in mind when
>>>> you have a multi-monitor setup).
>>> This limitation already applies to page flipping in general, it's not
>>> specific to FreeSync.
>> Maybe it shouldn't apply in general? After all, what if you have one
>> monitor with 60Hz and one with 90Hz?
> Page flipping can be used in that case. The application's buffer swaps
> will be synchronized to one or the other CRTC, by default the one where
> the largest part of the window is visible on. On the other CRTC(s), each
> flip may take effect slightly earlier or later than on the
> synchronization CRTC.

Hmm. I seem to have lost the plot and/or we're talking past each other. 
Maybe we need to go back to square one?

To rephrase the point that I was trying to get across: When you have a 
multi-monitor setup, and your application window covers (only) one of 
these monitors, then FreeSync will *not* be enabled.

At least that's how I understand the current DDX implementation, and I 
think it's surprising enough that it should be pointed out explicitly.

Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.

More information about the mesa-dev mailing list