Bug 486280

Summary:	plasma 6 screen blink/flashing with 2 monitors
Product:	[Plasma] kwin	Reporter:	slartibart70
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED FIXED
Severity:	normal	CC:	kde, nate, xaver.hugl
Priority:	NOR	Keywords:	multiscreen
Version First Reported In:	6.0.4
Target Milestone:	---
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	this video shows the flicker effect in plasma

Description slartibart70 2024-04-29 07:11:08 UTC

I have a 4K monitor connected to a laptop. All i did was checking out the new, shiny plasma6 on fc40, intensive browsing the web and opening/closing apps.

The 2nd (4K) screen suddenly showed 'artifacts' on the bottom half of the screen, like flashing insertions which disappeared immediately. You could sometimes see the contents, this looked like window contents of the browser, but distorted.
This happended with firefox and chrome

Any idea what this might cause?

===
Operating System: Fedora Linux 40
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.1.0
Qt Version: 6.7.0
Kernel Version: 6.8.7-300.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 PRO 7840U w/ Radeon 780M Graphics
Memory: 58,6 GiB of RAM
Graphics Processor: AMD Radeon Graphics
Manufacturer: LENOVO
Product Name: 21K5000JGE
System Version: ThinkPad P14s Gen 4

Comment 1 slartibart70 2024-04-29 11:45:31 UTC

just to add some info: this never happened at all in plasma5 running in fedora39

Comment 2 slartibart70 2024-04-29 12:56:57 UTC

and, this bug only happens on the 2nd monitor (dp-connection), not on the primary laptop-display

Comment 3 slartibart70 2024-04-30 06:20:20 UTC

Created attachment 169027 [details]
this video shows the flicker effect in plasma

Comment 4 slartibart70 2024-04-30 06:22:29 UTC

the video is not mine, i found it on reddit...
But it shows the distortion effect quite well.

the range goes from 'sometimes' to 'boah dude, this is unbearable, let's kill plasma'... if you know what i mean :-D

Comment 5 Nate Graham 2024-08-16 16:08:56 UTC

Probably a GPU driver issue; moving to KWin for now to see if there's anything we can do about it.

Has it happened again in Plasma 6.1?

Comment 6 Bug Janitor Service 2024-08-31 03:47:49 UTC

🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!

Comment 7 slartibart70 2024-08-31 20:24:18 UTC

as i found out, it mainly happened when the laptop monitor (built-in) was running with 90Hz, the 4K monitor with 60Hz
Putting both to 60Hz solved the problem.

Right now i'm testing with 90/60Hz again

Comment 8 Zamundaaa 2024-09-05 12:17:26 UTC

The glitches look the same as bug 480799. Does it also only happen on things that have blur behind them for you?

Comment 9 slartibart70 2024-09-05 12:22:38 UTC

After some testing, i can confirm no problems any more with different refresh-rates.
No glitches have been seen since

@Zamundaa: no, this was independent of screen-elemens blurring

This is my current config:

Operating System: Fedora Linux 40
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.5.0
Qt Version: 6.7.2
Kernel Version: 6.10.7-200.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 PRO 7840U w/ Radeon 780M Graphics
Memory: 58,5 GiB of RAM
Graphics Processor: AMD Radeon 780M
Manufacturer: LENOVO
Product Name: 21K5000JGE
System Version: ThinkPad P14s Gen 4

Works for me now, closing this ticket if you agree

Comment 10 Zamundaaa 2024-09-05 12:54:55 UTC

Great, then it was probably just some driver issue :)