Variable Refresh Rate

[emersion]

• Should we make the output commit fail if VRR can't be enabled? We don't know when VRR is indeed enabled, but in some cases we know when it fails. We still don't have support for test-only commits, so dealing with failures is going to be annoying for compositors.
• Sway implementation

Fixes: #1406
Depends on: #2046

Future work: Wayland protocol to opt-in to VRR.

[emersion]

This is ready for review. Reviewers will want to have a look at #2046 first.

[emersion]

Rebased against master.

[ddevault]

Can we bubble up whether or not the output supports adaptive sync, and add that to the swaymsg -t get_outputs response?

[emersion]

I've decided against bubbling up this information, because other backends (X11 and Wayland) won't be able to know.

[ddevault]

{SUPPORTED,UNSUPPORTED,UNKNOWN}

[emersion]

Can we bubble up whether or not the output supports adaptive sync, and add that to the swaymsg -t get_outputs response?

Done, but decided to report the current status instead, it's more reliable.

[ddevault]

Thanks!

[ruabmbua]

Wow this is amazing. Just tested it with my new setup, and I will never go back to windows, even for gaming.
Currently playing native shadow of the tomb raider on AMD graphics in sway, and I never had a better experience anywhere else.

Buttersmooth 160fps without any artifacts, and super low latency.