Bug 440639

Summary:	Black screen with cursor when resuming from sleep with a different display configuration
Product:	[Unmaintained] kscreenlocker	Reporter:	Simone Gaiarin <simgunz>
Component:	general	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	aldo-public, bshah, nate, plasma-bugs-null
Priority:	HI	Keywords:	regression
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Simone Gaiarin 2021-08-05 17:25:17 UTC

SUMMARY
The lock screen gets confused by multi monitor setups and shows a black screen with the mouse cursor if we change the monitors configuration while the notebook is sleeping.

Note if I disable 'lock after wake from sleep', the problem disappears.

STEPS TO REPRODUCE
1. With an external monitor connected through Notebook-DP > DP-HDMI adapter > Monitor-HDMI, put the notebook to sleep (it locks the screen)
2. Disconnect the HDMI cable
3. Wake the notebook up

ALTERNATIVE STEPS TO REPRODUCE
1. With an external monitor connected through Notebook-DP > DP-HDMI adapter > Monitor-HDMI, put the notebook to sleep (it locks the screen)
2. Wake the notebook up (lock screen is visible on both screens)
3. Disconnected the HDMI cable

OBSERVED RESULT
Black screen with cursor on the notebook screen


EXPECTED RESULT
Lock screen where I can type the password should be visible

Operating System: Manjaro Linux
KDE Plasma Version: 5.22.4
KDE Frameworks Version: 5.84.0
Qt Version: 5.15.2
Kernel Version: 5.10.53-1-MANJARO (64-bit)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i5-7200U CPU @ 2.50GHz
Memory: 15.5 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 620

Comment 1 Simone Gaiarin 2021-08-05 17:26:07 UTC

I started noticing the problem in the last 1-2 months.

Comment 2 Aldoo 2021-10-06 20:26:47 UTC

I am pretty sure I have this bug since way longer than a couple of months (much like several years, I think).

Also, there is the "reverse" reproduction: use your laptop unplugged, put it to sleep, plug it to an external monitor while asleep, then wake it up.
In this case, often (not always), one of the screens will be black. Also there are focusing issues, making the password hard to enter (not going more into details, as this deserves a separate bug report).

Since this is an old ongoing bug, I assume the resolution is probably difficult, and probably hardware dependent (by the way, like the opener, I use an Intel integrated GPU: Mesa Intel(R) UHD Graphics (CML GT2) (0x9bca)).

Maybe, until there is a proper fix, a workaround could be provided, making it easy to restart kscreenclocker when it is not usable? (I don't know, maybe a "panic" key combo of some sort, that does not require to switch to some other virtual terminal)

Also, is there no way for kscreenlocker to detect that the screen is currently black?

Comment 3 Aldoo 2021-10-11 07:15:03 UTC

Also probably related to Bug #436590 (about greeter not resizing on display configuration change: which probably share the same root cause, i.e. kscreenlocker is not aware of the change or does not react to it).

Comment 4 Aldoo 2021-10-11 07:21:07 UTC

Ah and Bug #412527 is also almost the same problem.
The three bugs are probable duplicates or symptoms of the same bug.

Comment 5 Nate Graham 2021-10-11 20:25:07 UTC


*** This bug has been marked as a duplicate of bug 412527 ***