PSR2 Selective Fetch causes underruns on Tigerlake

Continuing from the revert I sent regarding this:

https://patchwork.freedesktop.org/series/99796/

Basically it seems that since PSR selective fetch was enabled for Tigerlake in 7f6002e58025 ("drm/i915/display: Enable PSR2 selective fetch by default"), I'm suddenly seeing screen flickering that looks like an underrun whenever I move my cursor around on the left side of the screen (I assume cursor watermarks updating), along with seeing some underrun warnings in dmesg. Disabling selective fetch seems to fix the issue.

The system in question here is an X1 Carbon 9th Generation running Fedora Linux 35, and the problems can be reproduced with a kernel built from the latest drm-tip as of writing this. I'm using the variant of the X1 Carbon 9th gen with a 1920x1080 display as well.

Logs: dmesg.log

Video of flickering: PXL_20220208_214159483