I filed a bug with the KDE projects but I thought it might be helpful to share it here too.
Hardware:
GPU: RTX 4070
Connection: DisplayPort
Driver: 580.126.09 (proprietary)
Kernel: 6.17.0-14-generic
Desktop: Plasma 6 (KDE Neon 24.04)
Session: Wayland
HDR: Enabled
Issue:
When the DisplayPort monitor is powered off and then powered back on (either manually or via monitor sleep), the display does not recover under Wayland.
The system remains fully operational (SSH works), but the screen stays black permanently.
Restarting KWin does not restore output.
Only terminating the entire user session or rebooting restores display.
Important:
This issue does NOT reproduce under Plasma (X11). X11 recovers correctly from monitor power cycle.
Reproduction:
- Log into Plasma Wayland.
- Enable HDR.
- Power off DP monitor.
- Power monitor back on.
- Display remains black permanently.
This appears to be a DRM hotplug / connector re-acquisition failure specific to Wayland.
Upstream KDE bug:
Please let me know if a full nvidia-bug-report.log is required.