I have an issue with the GNOME screensaver, or to be more precise with the “screen blank” power-saving option. When not using the machine, after the configured timeout, the screens go blank and the monitors go to standby. However, about 2 seconds later GNOME decides to switch on the screens again. The screens then stay on for several seconds - and then briefly switch off again. And this endlessly repeats. Super annoying, since the screens keep flashing.
It’s not related to the monitors (I have three different ones connected/tested) - affects all of them. It’s also not related to any input device (keyboard/mouse). It also happens when no input devices are connected.
I’m looking for a log file which could explain why the gdm screen saver keeps waking up immediately after switching off the screens. I haven’t found any log messages yet, which would explain the behaviour.
Which log file specifically should I look into? And/or are there any debug switches to provide more verbose output about why the screen saver keeps waking up?
@thorstenbr Your running an AMD gpu I suspect, if so add the kernel boot option amdgpu.dc=0.
It’s an older machine using a Nvidia GTX660 with the nouveau driver.
So far, I assumed this to be related to GDM incorrectly detecting some kind of input - and therefore waking up. The delay between switching the screens on and off feels like the delay when you are moving the mouse - but then not making any input (entering the password to unlock). So it quickly goes back to screen power-save mode again (just to almost immediately wake up again). So I was hoping for some kind of log explaining which input exactly triggered GDM to show the lock screen again.
@thorstenbr ahh ok, then it should show in the output from journalctl. Perhaps open a terminal and then just tail the log journalctl -f and see if you can pick up what is happening.
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FWIW, I see similar behavior on my tumbleweed system with an Nvidia 3090ti and the proprietary drivers.
For me, the screens blank for a couple of seconds, then come on for a couple seconds, and then turn off and stay off - usually. Sometimes they come back on and never turn off again. It’s very inconsistent.
I’ve tried to dig into this a couple of times, but also have not found any logging anywhere that would explain this behavior.
It looks similar, but also looks to be specific to AMD GPUs, unfortunately. I’m trying to remember, but I think at one point, I was using a DP cable on one of the monitors, but the monitor I was using that on has a Chromecast plugged into it, so when the GPU on my PC would tell it to sleep, the input would change, so I never knew if that was actually showing the same issue.