SUMMARY While Adaptive Sync worked fine with my AMD card, it does not on my Intel Arc card. After some debugging and help from the folks over at the i915 bug tracker, we found that the root of the problem is that amdgpu allows for enabling/disabling VRR on the fly, while i915 requires a full modeset to toggle this setting. Even when the "Adaptive Sync" setting is set to "Always" it does not work. It appears that kwin does not enable VRR immediately when it enables the monitor. While the "Automatic" setting might prove difficult with the i915 driver because of this requirement, it should be possible to get the "Always" setting working on i915 devices by enabling VRR immediately when enabling the monitor. Triggering a full modeset when changing the setting from "Never" to "Always" or the other way around would also be required. To fix the VRR behaviour when set to "Automatic" a full modeset would be required every time a full screen application is started or stopped. This might not be desirable, and therefore maybe a helpful pop-up note explaining that the "Automatic" setting does not currently work with i915 is a better idea. STEPS TO REPRODUCE 1. Start wayland session 2. Enable VRR 3. Start full screen application OBSERVED RESULT No syncing of the refresh rate EXPECTED RESULT The refresh rate of the monitor is synchronized to the content SOFTWARE/OS VERSIONS Linux/KDE Plasma: Gentoo Linux, kernel 6.1.0-rc5 KDE Plasma Version: 5.26.3 KDE Frameworks Version: 5.100.0 Qt Version: 5.15.5 ADDITIONAL INFORMATION See also: https://gitlab.freedesktop.org/drm/intel/-/issues/7542
To be honest I don't think this is a thing that should be worked around in kwin, as it can cause other complications