i915 GPU HANG: ecode 7:1:85ddfffd on HP Mini 300-020 [bisected]

I filed a similar hang on the same system running an upstream kernel over a month ago in https://gitlab.freedesktop.org/drm/intel/-/issues/2106. I have now reproduced the issue on a recent clone of drm-tip. The drm-tip branch was cloned at this commit:

bee93e0c4c702 drm-tip: 2020y-08m-29d-01h-08m-26s UTC integration manifest

The GPU hangs occur whenever Cinnamon is started if I have booted a recent Linux upstream kernel. To be clear, the system will boot without problem to multi-user.target, but the hang occurs as soon as I transition to graphical.target and a desktop login is attempted. In contrast, I have never seen a GPU hang when running the Ubuntu Focal or Debian Buster kernels.

The system is an HP Pavilion Mini 300-020. The system is installed with Ubuntu Focal. The active display is attached with DP.

dmidecode, dmesg, and /sys/class/drm/card0/error output will be attached.

dmesg-20200829-073137.txt.bz2 dmidecode-20200831.txt.bz2 sys-class-drm-card0-error-20200829-075359.bz2