Bug 457755

Summary:	Plasmashell problems after changing the HDMI output and KDE does not recognize the new display
Product:	[Plasma] KScreen	Reporter:	myndstream
Component:	common	Assignee:	kscreen-bugs-null <kscreen-bugs-null>
Status:	RESOLVED UNMAINTAINED
Severity:	normal	CC:	kde, nate
Priority:	NOR
Version First Reported In:	5.18.8
Target Milestone:	1.0
Platform:	Debian stable
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description myndstream 2022-08-11 11:27:51 UTC

SUMMARY
***
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***
When I started a computer from standby after connecting the HDMI cable to another display, it didn't recognize the new monitor and still had the previous monitor set. There should be a rescan/refresh button in the Display system settings. It recognized the display after moving the HDMI cable back out and in again.

Furthermore, whenever I connect to another monitor the plasmashell seems to crash (I have to run killall plasmashell and kstart5 plasmashell, I don't know if it crashes or crashes all the time but the background image is black and the bottom panel is missing) and the konsole windows freeze. Could look into some logs if this is still a problem.

I don't know if this is already fixed or if there already is an issue for that.

Furthermore, when connecting the HDMI another monitor it should automatically change the resolution to the highest available for that monitor, not keep the current resolution which can result in no image at the new monitor until the resolution is lowered for all displays in the system settings

STEPS TO REPRODUCE
1. Connect HDMI to another monitor with a different resolution (with or without standby)
2. Connect HDMI back to the previous monitor

OBSERVED RESULT
Plasmashell problems after changing the HDMI output

EXPECTED RESULT
Changing the HDMI output should not result in any plasmashell problems and the output should work plug&play so any needed system settings are configured automatically.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian 11
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION

Comment 1 myndstream 2022-08-11 11:45:34 UTC

I don't know why you can't edit descriptions here. I'm using Wayland with KDE.

Comment 2 Nate Graham 2022-08-11 17:46:09 UTC

> KDE Plasma Version:  5.20.5
I'm afraid Plasma 5.20 is no longer maintained; I would recommend that you upgrade to 5.24 or later as soon as  your distros offers it.

Comment 3 myndstream 2022-10-01 22:28:48 UTC

I will upgrade as Debian releases a newer version (Debian 12 stable) and then test again. Why can't I edit the description or my comment? I'd like to add that:

the session ends only when the monitor that the HDMI cable is plugged into is turned off. The wallpaper is changed to a default one nevertheless. Currently, the remaining problem is that when doing one of these things to switch the monitor back again the sessions as well: a) pulling out the HDMI cable b) switching off the active second monitor c) press meta+p and selecting "Unify outputs" (haven't tried the other ones yet.

For the workout to be complete, I only need to find out how to switch back to the formerly active display without the session ending. I'll try a few more things later such as going into standby, then pulling out the HDMI cable, and waking it again. If somebody knows a working workaround, please comment.

Comment 4 myndstream 2022-10-09 15:22:44 UTC

May also be related to https://bugs.kde.org/show_bug.cgi?id=457996