Screen blacks out for a bit during lockscreen

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1

Hello,

Since a while now, after using Fedora 43 KDE with little to no issues, I have been stumbling upon some consmetic errors concerning the lockscreen in KDE, as well as possibly SDDM?

I have found that when booting the PC and being put in the initial login screen, I can enter my credentials as expected and log in to the DE as one normally would. However, I find that the splash screen that would normally play to indicate loading does not play under any circumstance. Even when setting to the splash screen to the built-in KDE Plasma and Fedora, the login screen changes to a solid, black screen, plays the login jingle, and flashes immediately to the desktop.

Similarly, when manually locking the session with a shortcut, which I have set to META+L, the kde lock screen is loaded, instead of SDDM. This works just fine as well, but the problem is that if the scree goes on standby on the lock screen (or the PC goes to sleep/suspend/hibernate? Not sure on this, I never was able to verify this despite these being turned off to my knowledge), when pressing a keyboard key to wake the display, it will show the time and the wallpaper. On the next key-press, it’ll show a solid, black screen for a few seconds and then show the time, media controls, user image and password entry, as if the transition animation was blacked out with a solid black screen.
I do have a video of this:

The monitor is wired directly to the GPU with a single HDMI to HDMI cable, with the mesa-freeworld drivers installed without issue.
The monitor itself is 100hz and set to 100hz @ 1080p, but a kscreen-doctor output shows that even before the animation would happen, the screen is set to 100hz, so it likely is not a display config change(?)
It also worked before, after installation, but I could not tell you what caused this in the first place.

I am using Fedora 43 with KDE, the official release
Gigabyte B850 Gaming x wifi6e
AMD Ryzen 5 9600x
ASRock Steel Legend RX 9070XT
16GB 6000Mhz CL30

What could be the issue here?

2

it’s probably a mode change, sddm screen uses a 60Hz refresh rate unless you configure it to the same refresh rate as the kde session.

3

I see! I can imagine that perhaps changing the splash screen and/or SDDM theme could have reset it back to 60hz after it was set to 100hz after a fresh install. I will see if I can figure out how to change the mode used by SDDM when I get access to my device.

Would a similar issue be going on during the KDE Lock Screen, as seen in the video? Can that be resolved in some way?

4

I don’t use KDE, so I don’t really know. But I see mode changes on GNOME too:
gdm at 60Hz and desktop configured to 144Hz. Lock screen remains at 144Hz though

See if reconfiguring desktop to 60Hz stops this behaviour. Then you know it’s a mode change. Enabling VRR can also introduce mode changes. Or lookup the current gfx mode in monitor’s OSD menu.

5

After doing some testing, I find that setting the settings to 60 Hz in KDE plasma does not alleviate the issue with SDDM. I can also see that on boot, the selected mode is 1080p 100Hz, so the issue does not seem to be a modeset?

My monitor is not capable of VRR, so that cannot be it.

I can at least verify that the OSD menu vanishes when the screen goes black, so it really is performing a modeset. But as to why, when the monitor itself reports running at 100hz at all times, I don’t know.

6

A quick update on this issue. I’ve found that booting into an older version of the kernel in the boot options doesn’t resolve the issue. I’ve not tried going a major version down yet. I’m not sure if it could be related to the issue.