Plasma Desktop Flickering - where to start? [SOLVED]

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43

Hi guys,

I rarely post because 99.9% of the time, i found solutions by using the search button. No luck this time.

I recently upgraded my workstation (after a whole year of being offline), went somewhat smoothly.
However, the desktop is flickering, and I am not sure where to start troubleshooting.

Just to be clear, it is "only what it is on the desktop itself that flickers". Like, the browsers, KDE menu, dolphin, etc are NOT flickering.
So basically, widgets, folder views etc. Which is odd (and annoying!).
I tried removing, re-adding them, but same behavior.

System info

alamahant · Advocate Joined: 23 Mar 2019 Posts: 3879

They say nouveau can be buggy?
Plz add

NeddySeagoon · Posted: Sat Dec 04, 2021 5:41 pm Post subject:

Sharp_Rulez,

Your emerge --info is truncated. Please share it all.

dpshak · Posted: Thu Dec 09, 2021 8:33 am Post subject:

Let me bump this back up to the top, to see if anybody has found a solution...

I have a similar problem. Here's my emerge --info:

dscharalampidis · n00b Joined: 07 Dec 2021 Posts: 18

Just an idea.

What happens if you disable the compositor in the KDE Settings?

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43

Hi guys,

Sorry about that; when i looked back the forum was down, and then i obvously got busy at work.

I'll attach below the whole info in case you still want to go through, but in the mean time, i'll check what you have suggested above!
Keep you posted if anything fixes it!

Thanks again

EDIT: just updated the video driver list, cleaned old packaged as per suggestion, remove old xorg config; also tried with clean .config / .kde4 (just in case) -- no change, widgets are still flickering. Posted the updated emerge info below!

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43

After doing the above, I checked xorg.log. I cant see anything standing out except these two items (not quite relevant tbh)

[ 27.925] (EE) Failed to open authorization file "/var/run/sddm/{21d6007a-42e2-477b-bf43-a41996a94521}": No such file or directory
[ 213.438] (EE) event4 - Metadot - Das Keyboard Das Keyboard: client bug: event processing lagging behind by 19ms, your system is too slow

I'm a bit puzzle about the sddm permission as it started correctly (?). I'll google about it later on.

My feeling is this could be simply a bug in KDE (not sure to which package belongs the widgets though!)

wjb · Posted: Sat Dec 11, 2021 1:35 pm Post subject:

It's probably worth investigating the "too slow" messages. Is there any sign of a runaway process, log messages streaming out, disk full, paging, ...

It might help to know the system hardware, cpu/ram/gpu

Bill

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43

oh well, might have found something.

I just booted up my previous kernel (5.9.14) and had no flickering issues.
Moved back to my current one (5.15.3) and flickering is back.

Weird that it just impact widgets on the desktop and nothing else; but that is a starting point.
Running out of time for today..

@dpshak: i read you have a similar issue, and also noticed you are on 5.15.6. Do you have your previous kernel to check if it clears the problem as well?

EDIT: for the record, i'm always building a vanilla kernel, not a gentoo one.

dpshak · Posted: Thu Dec 16, 2021 9:30 am Post subject:

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43

Sorry i was offline for a while; i'm giving it another try.

Since the rootcause appears to be related with 5.15, i'm bumping up to latest 5.15(.12) hoping it will clear my issue. I change one setting with regards to nouveau inside the kernel.

Let's see. Keeping you posted!

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43

same issue on 5.15.12 (with compositor disabled).

I'm tempted to just rollback to pre 5.15 and forget about it until next time. Cant find any easy solutions apparently

tomtom69 · Posted: Sat Jan 01, 2022 10:21 am Post subject:

same here with kernel 5.15.11. When I boot the last stable kernel (5.10.76) the flickering disappears.
I am also using nouveau. Maybe we can narrow down the issue to the graphics card used?
My one is
VGA compatible controller: NVIDIA Corporation GK208B [GeForce GT 710] (rev a1)
Subsystem: NVIDIA Corporation GK208B [GeForce GT 710]
Kernel driver in use: nouveau

Hu · Moderator Joined: 06 Mar 2007 Posts: 21607

I see a few options for people affected by this:

Permanently pin on <5.15. This will eventually fail.
Try a 5.16-rc to see if the kernel developers already fixed the problem, possibly without even realizing it.
Bisect the changes between v5.14 (which some users here report to work properly) and v5.15 (which is broken) to find exactly which commit introduces the regression. Once that is known, the regression can be reported to the kernel developers.

For the last option, the bisection could be speculatively narrowed to only the files relevant to the graphics driver. We don't know with confidence that it is a change in the Nouveau code specifically, but it seems reasonable under the circumstances, and it would greatly reduce the search space.

tomtom69 · Posted: Sat Jan 01, 2022 6:42 pm Post subject:

Meanwhile I found a solution that works for me. There seems to be an issue with kernel 5.15 and nouveau, but there is already a patch. More information here:
https://lists.freedesktop.org/archives/nouveau/2021-December/039609.html
https://cgit.freedesktop.org/drm/drm-misc/commit/?h=drm-misc-fixes&id=67f74302f45d5d862f22ced3297624e50ac352f0
I applied this patch to Kernel 5.15.11 and the flickering disappeared :-)
Hope this is a solution for others, too.

Sharp_Rulez · n00b Joined: 17 Sep 2006 Posts: 43