[RESPONDED] White flickering in Kubuntu 23.10, AMD R7 13"

I’m having an issue in Kubuntu 23.10 with a white flickering screen, but only in three circumstances: when full screening web pages, full screening video, and when messing with the scale setting in Display Configuration.

I’m using a 13" AMD Ryzen 7

See link for examples: https://photos.app.goo.gl/QHKasUK2kZVzgUN58

After a few weeks of puttering around, I’ve noticed several things:

This is a Firefox and Wayland specific bug. Both Brave and Chromium browsers are not experiencing this full screen white flickering, and neither is VLC media player for that matter.

This bug seems to be coming up because I’m using scaled elements in Plasma through Firefox.
Enabling widget.wayland.fractional-scale.enabled in about:config eliminates this bug, but introduces a new bug where menus and tooltip bubbles are not drawn correctly. This new issue is known already to the wayland/firefox community, I think.

Hi @William_Coolman,

I have Fedora installed at the moment on my Ryzen 7, so I did a quick test there. Note, we do not test against anything with KDE at this time, so when I tested against Ubuntu 22.04.3 (OEM C kernel) and Fedora 39 (fully updated), we did not see any of this.

Would be worth trying a live USB of Ubuntu 22.04 (which comes with the 6.5 generic). See if the same issue appears on the live USB in testing (again, LTS and GNOME).

Ok, I’ll give the live image a shot, report my findings.

Just today, I found another user that has nearly the exact same issue in full screen games on Reddit in the regular flavor of Ubuntu 23.04.3 LTS:

Have you tried increasing RAM reserved for GPU by setting in bios UMA_Game_Optimized and/or adding the amdgpu.sg_display=0 parameter to the kernel cmdline?

I use 23.10 with gnome and I had to do both to have a good experience.

This is good advice. Ideally, increasing RAM reserved for GPU by setting in bios UMA_Game_Optimized should address this without the need for the parameter.

Welp, I thought it fixed it for a while, but I’m still getting the flickering in Firefox. This is even after updating Firefox to Mozilla’s new .deb package.

I have not tested the off-site https://www.mozilla.org/ Firefox deb package as Ubuntu is best supported with snaps (and soon, I expect this will be the main option).

I’d sync your browser contents with browser sync in Firefox, purge it.

Assuming the Snap version wasn’t removed:

snap refresh

It will prompt for your user password, reboot.

If this is happening on 23.04, I’d test this against the tested/support 22.04.