https://bugs.kde.org/show_bug.cgi?id=518732
Bug ID: 518732
Summary: KWin does not retry output configuration after DRM
modeset permission failure on resume from suspend
Classification: Plasma
Product: kwin
Version First 6.6.3
Reported In:
Platform: Arch Linux
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
KWin does not retry output configuration after DRM modeset permission failure
on resume from suspend
STEPS TO REPRODUCE
1. Have a multi-monitor setup (2x DisplayPort) with an NVIDIA GPU on Wayland
2. Configure output priorities in System Settings (e.g., DP-2 as primary)
3. Suspend the system and resume
OBSERVED RESULT
On every resume, KWin logs:
kwin_wayland: atomic commit failed: Permission denied
kwin_wayland: Failed to open drm node: "/dev/dri/card0"
kwin_wayland: Atomic modeset test failed! Permission denied
kwin_wayland: Applying output configuration failed!
KWin does not retry. The stored output configuration from
kwinoutputconfig.json
(including priorities) is never reapplied. Output priorities revert to DRM
enumeration order, which may differ from the configured layout. The panel and
system tray shift to the wrong monitor.
EXPECTED RESULT
KWin should retry applying the output configuration after a transient DRM
permission failure on resume, using backoff or waiting for DRM readiness. The
stored output priorities, positions, and scales in kwinoutputconfig.json
should
be reliably applied after resume.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
KDE Plasma Version: 6.6.3
KDE Frameworks Version: 6.24.0
Qt Version: 6.11.0
Kernel: 6.19.11-arch1-1 (64-bit)
GPU: NVIDIA GeForce RTX 3090 (nvidia-open 595.58.03)
Monitors: 2x LG UltraFine 4K via DisplayPort
ADDITIONAL INFORMATION
The NVIDIA driver package ships a systemd drop-in at
/usr/lib/systemd/system/systemd-suspend.service.d/10-nvidia-no-freeze-session.conf
that sets SYSTEMD_SLEEP_FREEZE_USER_SESSIONS=false. This disables user
session
freezing during sleep so the NVIDIA kernel module can handle its own
suspend/resume sequence.
With sessions unfrozen, KWin attempts to reacquire DRM master before the DRM
subsystem is fully reinitialized, resulting in the permission error. KWin
treats
this as terminal and does not retry. Tools like kscreen-doctor can
successfully
apply the same configuration ~500ms later, confirming the DRM subsystem
recovers quickly.
Workaround: a systemd oneshot service on suspend.target that runs
kscreen-doctor to reapply positions/scales/priorities, followed by
qdbus6 org.kde.plasmashell /PlasmaShell org.kde.PlasmaShell.evaluateScript
'panels()[0].screen = 0;' to force the panel back to the correct screen.
Reproducibility: 100% on every resume from suspend.
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