VRR breakers

[UjinT34]

Multi-monitor

Multi-monitor doesn't work with nvidia (vrr activates but refresh rate is stuck at max) https://forums.developer.nvidia.com/t/feature-g-sync-freesync-under-wayland-session/220822/116?page=2. Others should work fine.

Animations

Any running animation will break VRR.

Cursor

DIfferent cursor setting combinations might break VRR. Frames scheduled by HL and AQ should be handled by cursor:no_break_fs_vrr. The breakage comes from excessive _CWlSurfaceCommit calls. Those extra calls are observed when pointer frame is sent with lock constraint active or a HW cursor buffer is present with atomic modesetting.

Games that use cursor lock usually hide the compositor cursor. They might still render cursor themselves. This is still counts as an invisible cursor.
Some games might switch between different modes, e.g. locked invisible during gameplay and unlocked visible in menus.
I don't know any games that might have locked != invisible.
Assuming cursor:no_break_fs_vrr = true and cursor:min_refresh_rate less than the target framerate:

HW	Locked	Invisible	Status
—	—	—	works
—	—	✓	untested
—	✓	—	untested
—	✓	✓	works with #6877
✓	—	—	breaks VRR
✓	—	✓	untested
✓	✓	—	untested
✓	✓	✓	works with #6877

Does anyone has a different experience? Are there any wayland compositors that have a working VRR with HW cursors and atomic modesetting?

[Atemu]

Thanks a bunch for the info (and the PR!).

How would one deduce whether the cursor is locked or whether they render it themselves?

[UjinT34]

With HYPRLAND_TRACE=1 #6877 should output listener_commitWindow skip to the log when it skips unwanted frames for a locked cursor. First-person shooters and 3rd-persom games with direct mouse camera control usually use locked hidden cursors. Most of them render the cursor in menus themselves. Some might switch to a visible unlocked cursor. Witcher 3 probably does that.