Bug 511916

Summary:	Plasma doesn't recognize proper resolution (and device?) after monitor is back after being turned off due to power saving settings
Product:	[Plasma] kwin	Reporter:	zupnikszydlik
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	kde, kdedev, xaver.hugl
Priority:	NOR
Version First Reported In:	6.5.2
Target Milestone:	---
Platform:	Manjaro
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Correct resolution Incorrect resolution output of 'drm_info' after triggering the issue

Description zupnikszydlik 2025-11-10 15:25:37 UTC

SUMMARY
When the monitor turns on after being turned off due to power saving settings (Settings > Power Management under the "Display and Brightness" section), Plasma shows a notification about the display being disconnected. The maximum supported resolution in settings is then set to 640x480, with the message: "640 x 480 (4:3)" is the only resolution supported by this display. To fix this, you have to turn the monitor off and on again, after which a notification about a new display being connected pops up.

STEPS TO REPRODUCE:
1. Wait until the monitor is turned off automatically
2. Move your mouse or press any key to turn the monitor back on
3. Observe the incorrect resolution

OBSERVED RESULT
Plasma sets an incorrect resolution after the monitor is turned on again.

EXPECTED RESULT
Plasma should restore the proper resolution after the monitor is turned on again

SOFTWARE/OS VERSIONS
Operating System: Manjaro Linux 
KDE Plasma Version: 6.5.2
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0
Kernel Version: 6.12.57-1-MANJARO (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 3600 6-Core Processor
Memory: 16 GB of RAM (15.5 GB usable)
Graphics Processor: NVIDIA GeForce GTX 1070


ADDITIONAL INFORMATION
Size of applets like app launcher or notifications is set to minimum (perhaps because of the 640 x 480 resolution).

Comment 1 TraceyC 2025-11-13 20:31:00 UTC

Thanks for the bug report. Can you provide the output of this command, both while the screen is at the correct resolution, and when the bug presents?

kscreen-doctor -o

Thanks.

Comment 2 zupnikszydlik 2025-11-14 12:01:04 UTC

Created attachment 186771 [details]
Correct resolution

Output of "kscreen-doctor -o" with correct resolution

Comment 3 zupnikszydlik 2025-11-14 12:01:43 UTC

Created attachment 186772 [details]
Incorrect resolution

Output of "kscreen-doctor -o" with incorrect resolution

Comment 4 zupnikszydlik 2025-11-14 12:03:13 UTC

I’ve attached two files: one showing the correct resolution and another showing the incorrect resolution.
I noticed it gives different ID when the bug occurs.

Comment 5 TraceyC 2025-11-14 21:04:55 UTC

Thanks for the information, that's useful. I see that when the display has the wrong resolution, kscreen-doctor only shows that one resolution:

Modes:  1:640x480@59.94*! 

I'd like to ask for one more thing. Please attach the output of `drm_info` after triggering the issue. Thanks!

Comment 6 zupnikszydlik 2025-11-14 23:33:29 UTC

Created attachment 186799 [details]
output of 'drm_info' after triggering the issue

As requested, I ran the command and here is the output

Comment 7 TraceyC 2025-11-17 17:15:22 UTC

Thanks for the attachment. I'll let the kwin developers take it from here.

Comment 8 Zamundaaa 2025-11-27 21:35:03 UTC

640x480 resolution is an easy tell for the graphics driver failing to read the EDID from the screen. Please report this at https://forums.developer.nvidia.com/c/gpu-graphics/linux