that's probably not it ... could you give the output of "ls /sys/class/drm" and "cat /sys/class/drm/*/enabled" and maybe enable "LogLevel=debug" in /etc/systemd/system.conf and reboot/try to syspend/add the journalctl log to the bug?
that's probably not it ... could you give the output of "ls /sys/class/drm" and "cat /sys/class/ drm/*/enabled" and maybe enable "LogLevel=debug" in /etc/systemd/ system. conf and reboot/try to syspend/add the journalctl log to the bug?