Random flickering with i915 on Linux 6.8

[Eugene San]

After migrating Mantic 23.10 install to Linux 6.8.0, I am experiencing heavy flickering at random.
It happens after a moderate to heavy on screen activity like window switching, scrolling etc.
It never happens when playing video or when there is no interaction using keyboard/pointer.

It tend to happen when the mouse cursor is in the bottom quarter of the screen and stops immediately when the cursor leaves that screen region.
Around the same time the following appears in kernel log:
kernel: i915 0000:00:02.0: [drm] *ERROR* CPU pipe A FIFO underrun

Happens on both X11 and Wayland on both KDE plasma and Mate (though less).

I first encountered the issue with Linux 6.8.0-11 and it still happens with Ubunutu's 6.8.0-28 and Mainline 6.8.7.
Kernels 6.6, 6.5, 6.1 and older did not have that issue.

Hardware is: Dell XPS 9350, Vendor Intel, Driver i915, Skylake GT2 [HD Graphics 520]
Software: Ubuntu 23.10, KDE Plasma 5.27.10 / Mate 1.26

Attaching kernel log for 6.8.0-28

[lotuspsychje (lotuspsychje)]

Thank you for filing this bug and make Ubuntu better!

In order to collect all your system info and relevant logs

please execute: apport-collect 2062951 from your terminal

so the developers can start debug your bug a better way

Thank you!

[Eugene San (eugenesan)]

Update:
I did some preliminary testing and it seems like adding "intel_idle.max_cstate=4" to cmdline resolves the issue but probably at the power efficiency cost.

I also tried "i915.enable_psr=0" but it didn't help just made the flickering a slightly different.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.