Bug 414626

Summary:	kwin_wayland on DisplayLink/udl turns screen off, and back on every frame
Product:	[Plasma] kwin	Reporter:	bluescreenavenger
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED REMIND
Severity:	normal
Priority:	NOR
Version First Reported In:	git master
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description bluescreenavenger 2019-11-28 17:20:56 UTC

SUMMARY


STEPS TO REPRODUCE
Need a Displaylink 2 device, (one that uses the UDL device
start kwin_wayland on the displaylink device. I usually move the main integrated card0 into another seat, so that the DisplayLink card is the only dri device in seat0

start a simple application that doesn't change often, like xterm, or konsole.
Press a key, or move the mouse. Observe the screen switch off, then back on

OBSERVED RESULT
Nothing interesting appears in the stdio/stderr log. I'm not sure the correct QT_LOGGING* variables to export...

EXPECTED RESULT
Weston runs on UDL, (the GL render works with a mesa patch workaround), but it runs with the --use-pixman flag, so I'd expect it to run like Weston.

It needs a newer kernel (from past some 5.something version that I forget.) Nothing worked at ALL before on UDL

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Linux 5.3.0 (Debian Buster (with the kernel from Debian Bullseye)
KDE Plasma Version: Master
KDE Frameworks Version: Master
Qt Version: 5.14

ADDITIONAL INFORMATION

Comment 1 bluescreenavenger 2019-12-19 03:47:26 UTC

I am willing to test with adding debug lines in places, trying workarounds, etc.
It happens every time a frame changes. I can open say, Konsole, and the screen will flash every time I move the cursor, or every time I type a letter into Konsole

Comment 2 bluescreenavenger 2019-12-23 03:57:15 UTC

Eh, now I can't seem to replicate it...