Bug 501889

(also submitted to NVIDIA)

Description:

Under Wayland on Kubuntu 24.10 with NVIDIA driver 570.86.15, turning off and on a Samsung G95SC monitor (connected via DisplayPort to an RTX 4070 SUPER) results in a blank screen requiring a TTY switch (TTY3 → TTY1) to restore the display. The same issue occurs when taking screenshots with Spectacle. Downgrading to driver 550 (e.g., 550.54.14) resolves both problems, with the display and screenshots working normally.

Environment:

OS: Kubuntu 24.10 (Plasma 6, Wayland session)
Kernel: [Insert your kernel version, e.g., uname -r output like 6.11.0-9-generic]
GPU: NVIDIA GeForce RTX 4070 SUPER
Driver: 570.86.15 (broken), downgraded to 550 (fixed)
Monitor: Samsung G95SC (OLED, likely 5120x1440 @ 240Hz), DisplayPort connection
Compositor: KWin (Wayland)
Steps to Reproduce:

Boot into a Wayland session on Kubuntu 24.10 with NVIDIA driver 570.86.15.
Connect an RTX 4070 SUPER to a Samsung G95SC via DisplayPort.
Turn the monitor off, then back on after a few seconds.
Result: Blank screen, monitor enters "no signal" countdown. Switching to TTY3 and back to TTY1 restores the display.
Alternatively, open Spectacle and take a screenshot.
Result: Same blank screen, same TTY workaround needed.
Expected Behavior:

Monitor should wake immediately with the desktop visible after being turned back on.
Screenshots with Spectacle should complete without blanking the display.
Actual Behavior:

With driver 570.86.15, monitor reconnection fails (blank screen, "no signal" countdown).
Spectacle screenshots trigger the same blank screen.
Logs show Qt apps creating "fake screens" and Wayland globals dropping (e.g., qt.qpa.wayland: Creating a fake screen in order for Qt not to crash, foot: warn: wayland.c:1467: unknown global removed).
Logs (from 570.86.15):

Mar 22 16:54:20 hexoid plasmashell[3846]: qt.qpa.wayland: Creating a fake screen in order for Qt not to crash
Mar 22 16:55:21 hexoid foot[4011]: warn: wayland.c:1467: unknown global removed: 0x00000045
Mar 22 16:55:22 hexoid kernel: workqueue: nv_drm_handle_hotplug_event [nvidia_drm] hogged CPU for >10000us 4 times
(Full logs available if needed—fake screen messages repeat, hotplug warnings occasional.)

Resolution:

Downgraded to NVIDIA driver 550 (e.g., 550.54.14 via sudo apt install nvidia-driver-550).
After reboot, monitor wakes instantly, and Spectacle screenshots work without issues.
Additional Notes:

Tested with nvidia-drm.modeset=1 in GRUB (GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nvidia-drm.modeset=1"); reduced hotplug warnings but didn’t fix the issue.
X11 session (Plasma X11) works perfectly with 570.86.15—no blank screen on monitor wake or screenshots.
Suspect a regression in 570.86.15’s Wayland hotplug/output handling with KWin.
Request:

Please investigate driver 570.86.15’s Wayland compatibility with high-res monitors like the Samsung G95SC.
Confirm if this is a known issue or fixed in a later release (post-570.86.15).