Desktop is flickering/out of focus

[Jonas Gamao]

Bug report on KDE's bug tracker: https://bugs.kde.org/show_bug.cgi?id=405920

The desktop is out of focus/flickering, like when a person is trying very hard to focus.

Here's a video demo, which was from 18.10: https://youtu.be/Gn_dITHQFEs

In Cosmic, the problem occurs after waking up from sleep. Now, it occurs all the time.

Operating System: Kubuntu 19.04
KDE Plasma Version: 5.15.3
KDE Frameworks Version: 5.56.0
Qt Version: 5.11.3
Kernel Version: 5.0.0-8-generic
OS Type: 64-bit
Processors: 4 × Intel® Core™ i5-6500 CPU @ 3.20GHz
Memory: 15.6 GiB of RAM
GPU: GTX 1060

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: plasma-desktop 4:5.15.3.2-0ubuntu1
ProcVersionSignature: Ubuntu 5.0.0-8.9-generic 5.0.1
Uname: Linux 5.0.0-8-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.10-0ubuntu23
Architecture: amd64
CurrentDesktop: KDE
Date: Tue Apr 2 06:45:14 2019
InstallationDate: Installed on 2019-04-02 (0 days ago)
InstallationMedia: Kubuntu 19.04 "Disco Dingo" - Alpha amd64 (20190326.1)
SourcePackage: plasma-desktop
UpgradeStatus: No upgrade log present (probably fresh install)

[Jonas Gamao (yamiyukisenpai)]

After enabling Flipping, it happens much less frequently, but it still happens a whole lot more compared to 5.14.

[Jonas Gamao (yamiyukisenpai)]

This is an example of it, but it's not as crazy because it happens less frequently compared to that: https://youtu.be/Gn_dITHQFEs

Still happens frequently enough that it gets annoying.

[Rik Mills (rikmills)]

Don't think any of our testers on Nvidia have mentioned this, but I will pass it on to see.

May be helpful to know what Nvidia card/chip you have, and what driver version from where is in use.

[Jonas Gamao (yamiyukisenpai)]

GPU: GeForce GTX 1060 60GB
VBIOS: 86.06.0e.00.20
Driver: 418.56

[Jonas Gamao (yamiyukisenpai)]

Hope this one helps, too.

[Darin Miller (darinmiller)]

I confirm this issue. I see flickering/screen flashing after waking from sleep on a GTX 1080 card, NVidia driver 418.56. Disabling compositiing kills the flicker, but flicker returns upon compositing e-enable.

Plamsa and kwin restarts fail to rectify. Reboot is the only sure fix.

[Jonas Gamao (yamiyukisenpai)]

That was my exact issue when I was in Kubuntu 18.10.

In 19.04, this happens even after boot.

[Jonas Gamao (yamiyukisenpai)]

I tried using XRender, but the problem is that it doesn't play nice with multiple monitors.

[Jonas Gamao (yamiyukisenpai)]

I created a new user account, and I am now trying to isolate the problem, such as which desktop effect would cause this to occur.

[Jonas Gamao (yamiyukisenpai)]

I forgot to mention that flickering is not occurring in the new user account.

[Jonas Gamao (yamiyukisenpai)]

I think there has to be a setting that's causing it to not play with NVIDIA. Problem is, I don't know where it is.

[Jonas Gamao (yamiyukisenpai)]

A little update

I think what truly solved it was erasing the `.nvidia-settings-rc` file, and have NVIDIA X Server Settings regenerate it again. After resetting the everything related to Plasma, turns out my last resort was erasing that file.

Pretty sure that's what solved it, but I'd like others to try to be sure.