Bug 482462

Summary:	Fullscreen applications freeze on input (Wayland) after update to Neon 6.0
Product:	[Plasma] kwin	Reporter:	Bela Drescher <kde>
Component:	multi-screen	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	jr, kde, nate, neon-bugs-null, sitter, vlad.zahorodnii, xaver.hugl
Priority:	NOR	Keywords:	multiscreen
Version First Reported In:	6.0.0
Target Milestone:	---
Platform:	Neon
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Bela Drescher 2024-03-05 12:38:43 UTC

SUMMARY
When switching any application to fullscreen or switching focus back to any application that already is in fullscreen, everything freezes for two seconds and my built-in monitor turns black until I focus any application that is not in fullscreen. If the fullscreen application is on my build-in monitor, everything works as expected. This only happens if I'm on Wayland, on X11 it works fine (But I can't use X11 because my built-in screen is HiDPI and i need to adjust scaling for each monitor).


STEPS TO REPRODUCE
1. Take Laptop with HiDPI monitor
2. Connect external FHD monitor
3. Play a youtube video in fullscreen on that monitor

OBSERVED RESULT
1. Everything freezes for two seconds when focusing browser
2. Build-in monitor turns black

EXPECTED RESULT
No freeze and no black monitor

SOFTWARE/OS VERSIONS
KDE Neon: 6.0
KDE Plasma Version: 6.0
KDE Frameworks Version: 6.0
Qt Version: 6.6.2
Graphics Platform: Wayland

ADDITIONAL INFORMATION
It's the same with and without nvidia drivers installed (version 535).
Build-in monitor: 3840x2160@60, scaling: 175%
External monitor: 1920x1080@60, scaling: 100%
Normally I have two external monitors connected and one time the problem were gone after disconnecting the second monitor. But I didn't manage to reproduce this.
It also happened once that changing the HiDPI monitor to FHD fixed the issue.
It doesn't happen on my second laptop with build-in FHD monitor.

Comment 1 Zamundaaa 2024-03-06 18:05:09 UTC

Do your displays support adaptive sync? This sounds similar to bug 481750 (fixed in 6.0.1)

Comment 2 Bela Drescher 2024-03-06 20:23:25 UTC

My external monitor definitely supports adaptive sync. For the internal one I'm not sure, but the laptop isn't old so it should (It's a ThinkPad P15v).
I've looked in jounalctl now and noticed one related error which does not appear in the bug you linked, so I don't think it's related:
`Mär 06 20:54:41 ThinkPad-Untbu kernel: i915 0000:00:02.0: [drm] *ERROR* Timed out waiting PSR idle state`
Adding the kernel parameter `i915.enable_psr=0` solves the problem (as mentioned in https://bbs.archlinux.org/viewtopic.php?id=213495, even though this is for a much older kernel).

Comment 3 Zamundaaa 2024-03-06 20:34:18 UTC

Okay, then it's a driver bug, which you can report at https://gitlab.freedesktop.org/drm/intel/-/issues