Bug 509496

Summary: One monitor (always the same one) resets configuration upon wake from sleep
Product: [Plasma] kwin Reporter: Alastor Tenebris <livingnightmare>
Component: output configurationAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED UPSTREAM    
Severity: normal CC: kdedev, nate, xaver.hugl
Priority: NOR Keywords: multiscreen
Version First Reported In: 6.4.4   
Target Milestone: ---   
Platform: Bazzite   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Wayland ENV Debug
Kscreen Log
Output of drm_info

Description Alastor Tenebris 2025-09-14 20:19:57 UTC 
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***

SUMMARY
At seemingly random occurrences, when my computer wakes up from sleep, one of my monitors (it's always the same one) will reset itself to an unusable resolution (originally it was 1024x760, now it's 640x480), and it disconnects itself from my other monitor in System Settings, with no way of moving it to reattach it. This persists even if I log out, and seemingly the only way to fix this is to restart the computer.
STEPS TO REPRODUCE
1. Let the computer sleep
2. Wake up the computer from sleep

OBSERVED RESULT
The resolution resets.

EXPECTED RESULT
The resolution does not reset

SOFTWARE/OS VERSIONS
(available in the Info Center app, or by running `kinfo` in a terminal window)
Operating System: Bazzite 42
KDE Plasma Version: 6.4.4
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.1

ADDITIONAL INFORMATION
I had this issue happen on openSUSE Tumbleweed as well, so I don't think it is an OS issue.
Comment 1 Alastor Tenebris 2025-09-14 22:51:06 UTC 
After some more tests, unplugging and replugging in the monitor allows me to set the monitor back to the settings I originally had it on. Before replugging it in, the max resolution it gives me is 1440x480 at 60hz (this is a 1080p 165hz monitor).
Comment 2 TraceyC 2025-09-16 15:50:58 UTC 
Sending to kwin, which handles displays

When the resolution bug occurs, can you run this, and then paste the output into this report? 

kscreen-doctor -o

Then, please run kscreen-doctor with WAYLAND_DEBUG=1 when the wrong display resolution is set, and also attach KWin's log after trying to change the configuration. See this for the log location and getting debug log output:
https://community.kde.org/KWin/Debugging#Getting_debug_log_output

Thanks.
Comment 3 Alastor Tenebris 2025-09-17 02:17:49 UTC 
Created attachment 184994 [details]
Wayland ENV Debug
Comment 4 Alastor Tenebris 2025-09-17 02:18:35 UTC 
Created attachment 184995 [details]
Kscreen Log
Comment 5 Alastor Tenebris 2025-09-17 02:19:51 UTC 
Got two of the outputs, but KWin is refusing to output to a debug log even though I've set the environment variable in both bashrc and /etc/environment
Comment 6 TraceyC 2025-09-18 15:31:12 UTC 
Thanks for providing the information, I'll let the kwin folks take it from here.
Comment 7 Zamundaaa 2025-09-18 17:42:54 UTC 
When this happens, please get the output of drm_info and attach it here.
Comment 8 Alastor Tenebris 2025-09-20 01:14:33 UTC 
Created attachment 185110 [details]
Output of drm_info

I think this is the right program? Let me know if it isn't.
Comment 9 Zamundaaa 2025-09-26 15:08:32 UTC 
Yeah, it's the right one. So the kernel tells us the wrong list of modes, and then KWin falls back to the first mode in the list (as there isn't even a preferred mode). This could be from the kernel filtering out more modes than it should, or it simply not reading the EDID correctly.

You can report this at https://gitlab.freedesktop.org/drm/amd/-/issues. Attach the same drm_info output there, plus the drm_info output for when the display is recognized correctly.