Bug 493446

Summary: Screen turns off and on when switching between activities with external screen & laptop lid closed.
Product: [Plasma] kwin Reporter: ilya
Component: activitiesAssignee: KWin default assignee <kwin-bugs-null>
Status: REPORTED ---    
Severity: normal CC: xaver.hugl
Priority: NOR    
Version First Reported In: 6.1.4   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description ilya 2024-09-21 16:09:13 UTC 
SUMMARY
Screen turns off and on when switching between activities with external screen & laptop lid closed.
The bug *does not* appear when using both displays, laptop-only display (external disabled), or external display only when the lid is open.

Similar bug was described earlier here: https://bugs.kde.org/show_bug.cgi?id=460794

STEPS TO REPRODUCE
1. Connect external monitor to HDMI port
2. Switch to external screen (laptop screen goes blank) - this step can be omitted, just close the lid will probably work too
3. Close the lid
4. Switch between activities with any method, i.e. keyboard shortcut, or activity pager widget

OBSERVED RESULT
Screen goes blank for a second, with observable change in frequency (you can hear a quiet a high-pitched noise from the display, that usually accompanies changing resolutions). than the target activity shows up

EXPECTED RESULT
Activities should switch immediately as they are in most cases (i.e. with open laptop lid).

SOFTWARE/OS VERSIONS

Operating System: Arch Linux 
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.5.0
Qt Version: 6.7.2
Kernel Version: 6.10.6-zen1-1-zen (64-bit)
Graphics Platform: X11
Processors: 8 × AMD Ryzen 5 2500U with Radeon Vega Mobile Gfx
Memory: 14.5 GiB of RAM
Graphics Processor: AMD Radeon Vega 8 Graphics
Manufacturer: Acer
Product Name: Nitro AN515-42
System Version: V1.18
Comment 1 Zamundaaa 2025-01-07 12:56:40 UTC 
KWin doesn't do modesetting on X11. I'm not sure where this could be coming from, as KScreen doesn't have any activities integration, but it's definitely not KWin doing this.
Can you also reproduce this on Wayland?
Comment 2 ilya 2025-01-07 19:13:16 UTC 
(In reply to Zamundaaa from comment #1)
> KWin doesn't do modesetting on X11. I'm not sure where this could be coming
> from, as KScreen doesn't have any activities integration, but it's
> definitely not KWin doing this.
> Can you also reproduce this on Wayland?

Yes, the same behavior is observed on Wayland too (except the delay is a bit longer).
Comment 3 Bug Janitor Service 2025-01-22 03:47:38 UTC 
🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

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