Bug 475549

Summary:	Intermittent Flickering/Disappearance of Browser and Task-bar panels during Plasma-Wayland sessions.
Product:	[Plasma] kwin	Reporter:	Gary S. Martin <gmartin>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal	CC:	gmartin
Priority:	NOR
Version First Reported In:	5.27.8
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Video of flicker episode

Description Gary S. Martin 2023-10-13 04:45:48 UTC

Created attachment 162265 [details]
Video of flicker episode

SUMMARY
***
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See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***

STEPS TO REPRODUCE
1. Install Archlinux/NVIDIA Proprietary Driver/KDE Plasma/SDDM/Wayland per Archlinx Wiki
2. Select Plasma (Wayland) on SDDM Greeter, Enter Credentials, Select Login
3. Open Konsole terminal instance, Open Firefox browser instance

OBSERVED RESULT
Occasional flickering panel/window disappearance, primarily of the browser panel,  but sometimes of the task-bar panel, during which the desktop image behind the browser panel may be seen for periods ranging from a fraction of a second to 15 seconds. Other artifacts, such as stuttering during scrolling of text windows and slowed response of the mouse along with a paintbrush effect (see attached video) are also present. Occasionally, the trim of the browser panel (menu-bar, url-bar, & side panels) flicker/disappear while the central browser window is unaffected. None of these artifacts have been observed to affect the Konsole terminal panel so far.

The video attached is far from representative. It is difficult to record because none of the problems have ever been observed when screen recording was occurring (using OBS Studio). The problems only occur when the screen recorder is not running. As a result, I am only able to record evidence of the problem with my phone, which is less than ideal. Since the occurrences are frequent but relatively brief, it has been difficult to get a good video of the problems.

EXPECTED RESULT
No visual artifacts. Smooth mouse response and text scrolling.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Archlinux (updated today) 
(available in About System)
KDE Plasma Version: 5.27.8
KDE Frameworks Version: 5.110.0
Qt Version: 5.15.11
Kernel-Version: 6.5.7-hardened1-1-hardened (64-bit)
GPU: NVIDIA GeForce RTX 4060/PCIe/SSE2 (ASUS)
GPU Driver: NVIDIA Proprietary Driver (dkms) 535.113.01-2

ADDITIONAL INFORMATION

Comment 1 Gary S. Martin 2023-10-13 04:49:28 UTC

drm_info output: http://0x0.st/H4OY.txt

Comment 2 Gary S. Martin 2023-10-13 04:53:17 UTC

Output of qdbus org.kde.KWin /KWin supportInformation 
http://0x0.st/H4W1.txt

Comment 3 Gary S. Martin 2023-10-14 23:38:19 UTC

The flickering occurs less often and for generally shorter durations under the lts kernel than under the current kernel.

Comment 4 Gary S. Martin 2023-10-14 23:41:19 UTC

http://0x0.st/H4GM.txt
Under the lts kernel, simpledrm is deactivated as it should be.

Comment 5 Gary S. Martin 2023-10-15 07:09:35 UTC

Apparently, the browser (Firefox) issue is resolved by setting the environment variable MOZ_ENABLE_WAYLAND=1. (In Archlinux, you can set variables per wayland session in ~/.config/environment.d/envvars.conf, as described here: https://wiki.archlinux.org/title/Environment_variables#Per_Wayland_session.) I am trying that now and will mark this as solved if the flickering of the browser panel is not observed during the next couple of hours.

Comment 6 Gary S. Martin 2023-10-15 09:07:46 UTC

The Firefox browser panel flickering/disappearance problem was resolved by setting the environment variable MOZ_ENABLE_WAYLAND=1. 

Additional info for Archlinux users is available at these two wiki pages:
Firefox | Wayland : https://wiki.archlinux.org/title/Firefox#Wayland
Environment Variables | Per Wayland Session : https://wiki.archlinux.org/title/Environment_variables#Per_Wayland_session