Monitor not waking up after being turned off due to inactivity on Wayland only with 240Hz refresh rate

Graphics / Linux Linux
1

I am using KDE Plasma with Wayland on CachyOS. I have a weird problem when the screen turns off due to inactivity. I have a Samsung Odyssey G65B monitor running in 2560x1440 resolution and 240Hz refresh rate. When I let the screen turn off due to inactivity, the monitor tells me it doesn’t detect a signal, so it will go to standby mode in 60 seconds, which is normal. After it goes to standby mode, I shake the mouse to wake the system up. The screen flashes, which it usually does when being turned on or off, and I also hear KDE system sounds. However, instead of turning on, the screen tells me it can’t detect a signal, and it goes back to standby mode. Shaking the mouse more causes more system sounds to play, but the screen won’t wake up. I know the system does wake up, since I can blindly type my password to enter the desktop, and the keyboard lights up since its drivers take over. I can also blindly press a shortcut to open a terminal and type a command like sudo reboot now, and the system reboots. After reboot, everything is normal again.

So the system does wake up and the desktop session works, but the screen doesn’t pick up the signal. There are some weird conditions and consequences of this problem, which I am not able to understand.

  • The problem only happens on Wayland. If I switch to X11 and let the screen turn off and then wake it up, everything works fine. The screen wakes up, and I see the login screen.
  • The problem only happens on 240Hz. If I change the screen refresh rate to 120Hz or 60Hz, there is no problem. The screen wakes up, and I see the login screen.
  • Turning the monitor off and on usually doesn’t fix anything, but there was one time it did make the screen wake up. I am not able to reproduce it consistently, though.
  • If I press Ctrl+Alt+F3 to go to a virtual console, the screen wakes up and goes to the virtual console. Pressing Alt+F2 after that to return to the desktop session fixes the problem, and I see the login screen. This and rebooting are the only consistent workarounds to this problem I found.

My GPU is NVIDIA GeForce RTX 4070 SUPER. At the beginning, I thought it was a bug in KDE, but when I reported it to KDE, they told me it’s definitely a driver bug and I should report it here.

2

I’m using Xorg with a Samsung-Odyssey-G95SC + GeForce RTX 4060 (AD107-A) on Ubuntu 24.04. Similar issues, so it is probably correct, that this is not a KDE or wayland problem. I guess the Samsung firmware does strange things (assumes to be driven by ms windows bloat) and results in such a bad behavior (which happened in 22.04, too - so probably not an OS issue as well). Basically when the screen saver started, or when logged out [and turned the screen explicitly off] it was impossible to revive the screen. The only way I found to revive it was to restart Xorg (“Option “XKbOptions” “terminate:ctrl_alt_bksp”). I tried different drivers (565, 575, 580) so I tend to blame the monitor firmware. However, what I’ve done is to use the edid binary downloaded from the monitor - which seems to mitigate the problem a little bit (IIRC I re-enabled the screensaver, but not sure. Was a horror, when I left the workplace, came back later and the Xsession was not accessible/usable anymore). Also, because I have lightdm (login manager) running, when I’m coming back to my workplace and the monitor has been switched off, I first type 2-3 letters on the keyboard and after that I power on the monitor. This seems to work for ~ 8/10. The other 2 times I still need to Ctrl+Alt+Backspace (restart Xorg). FWIW I’ll try to attach my /etc/X11/xorg.conf .

xorg.conf.txt (2.7 KB)

3

Running Arch on Wayland with KDE Plasma and a Samsung C49RG9X. Although my display only maxes at 120hz, it still seems unable to wake with activity nor programmatically over SSH. Have to power cycle it and that makes unattended access with automatic login and lock with RustDesk, or to wake and jump into Sunshine/Moonlight impossible. Annoying, add I updated Samsung firmware to no avail.