SUMMARY *** My display comes with 4 different refresh rates: 60hz, 120hz, 144hz and 165hz. Since kwin 5.27.4, the screen refresh rate is stuck at 60hz whether I select 60hz, 120hz or 144hz from the Plasma display settings (confirmed by checking the screen OSD menu). It happens on both Wayland and X11 sessions. xrandr displays the selected refresh rate. Setting the refresh rate to 165hz works as intended though. Downgrading to kwin 5.27.3 solves the issue. *** STEPS TO REPRODUCE 1. Select a 120hz or 144hz refresh rate from Plasma display settings 2. Moving the mouse cursor / windows around seems sluggish 3. The screen OSD confirms that it's still running at 60hz SOFTWARE/OS VERSIONS Linux: Arch Linux KDE Plasma Version: 5.27.4 KDE Frameworks Version: 5.104.0 Qt Version: 5.15.8 ADDITIONAL INFORMATION My display is an Iiyama G-Master GB2770QSU-B1
Turning the monitor off and on again changes the refresh rate to the correct value. However it's still locked at 60hz when the system is rebooted.
I have the same problem with a Gigabyte FI32Q monitor, I'm also on Archlinux and the problem started when I upgraded to 5.27.4. On my monitor it's 170Hz that works, on all others (120,144,165) the fps meter on my monitor and the kde one under desktop effects shows 60 fps. Powering off and on the monitor also fixes the problem on my system.
Additional observation: if the screen goes into sleep mode then turns back on, it goes back to 60hz. But powering it off and on after that fixes the problem again.
Same for me on Dell S2721DGF since 5.27.4. When I select 120hz and 144hz it stays at 60hz. Switching display off/on is a temporary fix, but after reboot it is back to 60hz again. When I select 165hz it works correctly.
I have bisected this bug to this https://invent.kde.org/plasma/kwin/-/commit/dc95392b982ac9ae95a72e5f38e5ecc499f0bc19 commit
*** Bug 468304 has been marked as a duplicate of this bug. ***
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/3950
Just to document this, the linked MR is just a workaround. The kernel bug that caused this problem is being tracked at https://gitlab.freedesktop.org/drm/amd/-/issues/2501
*** Bug 468251 has been marked as a duplicate of this bug. ***
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/3951
Git commit 6f722954a03190ced4d317f6dde97d41650b5d34 by Xaver Hugl. Committed on 09/04/2023 at 10:26. Pushed by zamundaaa into branch 'master'. backends/drm: set the scaling mode to none Setting it to "Full Aspect" causes some problems with amdgpu, breaking switching the refresh rate between modes M +2 -2 src/backends/drm/drm_pipeline.cpp M +2 -2 src/backends/drm/drm_pipeline_legacy.cpp https://invent.kde.org/plasma/kwin/commit/6f722954a03190ced4d317f6dde97d41650b5d34
Git commit bbc3e10c589a01dfe8933fbe910412c3cd2dbac8 by Xaver Hugl. Committed on 09/04/2023 at 10:38. Pushed by zamundaaa into branch 'Plasma/5.27'. backends/drm: set the scaling mode to none Setting it to "Full Aspect" causes some problems with amdgpu, breaking switching the refresh rate between modes (cherry picked from commit 6f722954a03190ced4d317f6dde97d41650b5d34) M +2 -2 src/backends/drm/drm_pipeline.cpp M +2 -2 src/backends/drm/drm_pipeline_legacy.cpp https://invent.kde.org/plasma/kwin/commit/bbc3e10c589a01dfe8933fbe910412c3cd2dbac8