Bug 514240

Summary:	Built-in screen freezes on login if adaptive sync is not set to "Always"
Product:	[Plasma] kwin	Reporter:	Johannes Gäßler <johannesg>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	NEEDSINFO WAITINGFORINFO
Severity:	normal	CC:	xaver.hugl
Priority:	NOR
Version First Reported In:	6.5.4
Target Milestone:	---
Platform:	Manjaro
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	debug logs as for DRM

Description Johannes Gäßler 2026-01-06 19:30:38 UTC

SUMMARY

I am using an Asus ROG Flow Z13 laptop with a built-in screen. Using Manjaro with KDE, after I updated the system my screen would freeze upon login, though I could still hear applications opening. The freeze does not occur consistently. A fresh install of Manjaro v25 is working correctly for both KDE and XFCE, KDE breaks upon update and can be fixed by rolling the update back. Manjaro v26 can already freeze during the installation process. The problem seems to be caused specifically by adaptive sync, setting it to "Always" fixes the issue.

STEPS TO REPRODUCE
1. Start the Manjaro v26 KDE installer, the screen may freeze.
2. Install Manjaro and repeatedly log in or repeatedly launch the installer until the freeze occurs.

OBSERVED RESULT

The screen freezes, all other functionality (second screen, SSH) remains unaffected.

EXPECTED RESULT

The screen works correctly.

SOFTWARE/OS VERSIONS
Operating System: Manjaro Linux
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.21.0
Qt Version: 6.10.1
Kernel Version: 6.18.3-arch1-2-flowx13 (64-bit) (The bug is not specific to this kernel, it also occurs with the vanilla kernel)
Graphics Platform: offscreen
Processors: 32 × AMD RYZEN AI MAX+ 395 w/ Radeon 8060S
Memory: 128 GiB of RAM (121.5 GiB usable)

ADDITIONAL INFORMATION

The screen freezes if and only if adaptive sync is not set to "Always". If a second monitor is connected during login the bug does not occur. If a second monitor is connected after the login it does not unfreeze the built-in screen but the second monitor works correctly. If the built-in screen is turned off due to inactivity and then turned on again this unfreezes the built-in screen.

Comment 1 Zamundaaa 2026-01-08 20:56:50 UTC

Please get kwin and drm debug logs for the issue. The script at https://invent.kde.org/plasma/kwin/-/wikis/Debugging/Debugging-DRM-issues should work in this case

Comment 2 Johannes Gäßler 2026-01-11 14:09:34 UTC

Created attachment 188419 [details]
debug logs as for DRM

I am for some reason no longer able to reproduce the issue for my regular account, I created a new account "test" where the issue occurs on login without any changes to the default settings.

Comment 3 Zamundaaa 2026-01-13 21:14:12 UTC

The debug log shows KWin committing updates to the screen without any problems.
Please ssh into the system while its screen looks frozen, and get the output of drm_info. Then (blindly) move the cursor to some other spot, and get the output of drm_info again. That way we can be certain about whether or not KWin is still updating the screen, or if it's a driver bug.