Bug 468519

Summary: Display configuration is periodically reloaded after switching from external screen to internal laptop screen
Product: [Plasma] KScreen Reporter: Oleksii Zolotarevskyi <rockingcat>
Component: commonAssignee: kscreen-bugs-null <kscreen-bugs-null>
Status: RESOLVED NOT A BUG    
Severity: normal CC: nate, xaver.hugl
Priority: NOR    
Version First Reported In: 5.27.4   
Target Milestone: ---   
Platform: Neon   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Output of the command "journalctl -f" after switching to the internal screen.
The display configuration periodically reloads itself for no apparent reason. The display is in a sleep mode and constantly connected with a DisplayPort.

Description Oleksii Zolotarevskyi 2023-04-14 23:36:50 UTC
Created attachment 158118 [details]
Output of the command "journalctl -f" after switching to the internal screen.

After switching from the external screen to the internal laptop screen, the display configuration is reloaded each ~10 seconds.
Each time the configuration is reloaded:
	* The image on the internal screen stutters.
	* The icon of the applet "Display Configuration" blinks.
	* The notification "A new output has been added. Settings have been reloaded." is shown if the "Display Configuration" settings are opened.

When the external screen is turned OFF and ON again by the power button, the reloading does not happen anymore.

Each reloading of the display configuration is followed by the identical journalctl messages that start and end with "Emitting configChanged()" (as in the 1st attachment).

STEPS TO REPRODUCE
1. Connect an external screen to the laptop.
2. Switch to the external screen in the Display Configuration applet.
3. Switch to the internal screen in the Display Configuration applet.

OBSERVED RESULT
The display configuration is periodically reloaded.

EXPECTED RESULT
The display configuration is not reloaded.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: KDE neon 5.27 User Edition
KDE Plasma Version: 5.27.4
KDE Frameworks Version: 5.105.0
Qt Version: 5.15.8

ADDITIONAL INFORMATION
kscreen Version: kscreen/jammy,now 4:5.27.4-0xneon+22.04+jammy+release+build27
kwin Version: kwin-x11/jammy,now 4:5.27.4.1-0xneon+22.04+jammy+release+build35
Nvidia Driver Version: 525.105.17 (also reproducible on 530.41.03)
Comment 1 Nate Graham 2023-04-17 16:12:01 UTC
How is the screen connected? HDMI, DisplayPort, or something else?
Comment 2 Oleksii Zolotarevskyi 2024-03-31 15:49:51 UTC
(In reply to Nate Graham from comment #1)
> How is the screen connected? HDMI, DisplayPort, or something else?
The monitor is connected via DisplayPort.
Still happening on Manjaro with Plasma 5.27.10.
I think the issue is that the monitor cannot enter the sleep mode.
A few related bug reports:
https://bugs.kde.org/show_bug.cgi?id=413618
https://bugs.kde.org/show_bug.cgi?id=422455
https://bugs.kde.org/show_bug.cgi?id=426609

Can be marked as duplicate if necessary.

Sorry for the late answer!
Comment 3 Oleksii Zolotarevskyi 2024-05-30 17:56:46 UTC
Created attachment 169998 [details]
The display configuration periodically reloads itself for no apparent reason. The display is in a sleep mode and constantly connected with a DisplayPort.

Still present in Plasma 6.0.5
Comment 4 Zamundaaa 2025-01-10 17:32:51 UTC
Unfortunately this doesn't sound like something we can fix; some displays just trigger hotplug events while in standby mode, so they get processed and this happens :/
In the Wayland session, this should at least not cause any stutter though. If it does, please make a bug report for KWin about it!
Comment 5 Oleksii Zolotarevskyi 2025-01-11 21:09:17 UTC
Ok, thanks for the info.