Bug 420702

Summary:	Secondary monitor black after rotation
Product:	[Plasma] kwin	Reporter:	Roger Light <roger>
Component:	multi-screen	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED FIXED
Severity:	normal	CC:	rikmills
Priority:	NOR
Version First Reported In:	5.18.4
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Roger Light 2020-04-28 12:59:23 UTC

SUMMARY

I have two monitors, a landscape 1680x1050 (main monitor) and a portrait 1920x1080, rotated 90 degrees anticlockwise (secondary monitor). Nvidia graphics card, with the proprietary drivers.

When I log in, the secondary monitor is entirely black. If I move my mouse to the monitor, I can see it. If I try to drag a window to it, I can see the mouse cursor but no window.

If I use Ctrl-Alt-F2 to swap to a console, then swap back to the desktop the problem is resolved and I have a notification stating that kwin restarted desktop effects due to a graphics change.

STEPS TO REPRODUCE
1. Starting point - everything is displaying as expected, with one monitor landscape and the secondary monitor portrait
2. Open System Settings/Display Configuration
3. Disable the secondary monitor and click Apply
4. Enable the secondary monitor (this will have reverted to landscape mode) and click Apply
5. -> The monitor should now display the desktop as normal (although in the wrong orientation in my case)
6. Click on "90 degrees anticlockwise" orientation, then click Apply
7. -> The monitor will be black, with a visible mouse cursor

The same behaviour is shown going from no rotation to 90 degrees clockwise, or from 180 degrees rotation to either of the portrait orientations, but it works fine going from no rotation to 180 degrees.

OBSERVED RESULT

The secondary monitor is entirely black, but with a visible mouse pointer. Attempting to move windows to the secondary monitor shows the mouse pointer but no window.

EXPECTED RESULT

A normal desktop showing on the monitor.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Ubuntu 20.04
KDE Plasma Version: 5.18.4
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8

kwin version: 5.18.4.1-0ubuntu2

ADDITIONAL INFORMATION

This is easily reproduceable, I can provide more details / debugging if needed.

Comment 1 Roger Light 2020-05-05 09:30:14 UTC

I'm considering doing a clean reinstall, so if you'd like any debugging doing on this please let me know what I could do. I'm not afraid of gdb.

Comment 2 Roger Light 2020-05-05 22:48:13 UTC

I have done a clean install (but still have an image of the old install, although that's irrelevant). The problem persists. I created a fresh user and the problem is not present for that user, so it must be a user configuration issue.

Comment 3 Vlad Zahorodnii 2020-05-07 06:03:32 UTC

Just to be sure... Are you running an xserver per each monitor? or only one xserver?

Comment 4 Roger Light 2020-05-07 09:39:03 UTC

Just a single Xorg instance, sorry if multihead means multiple instances.

Comment 5 Roger Light 2021-07-20 08:42:34 UTC

This is no longer an issue as of at least 5.21.4.