Bug#1118261: Upgrading to 20250917-1 makes gdm not appear (only cursor in upper left)

[Johannes Schauer Marin Rodrigues <josch@debian.org>]

Package: firmware-misc-nonfree
Version: 20250917-1
Severity: serious

Hi,

on Debian unstable with firmware-misc-nonfree 20250917-1, gdm does no
longer start (only cursor in an otherwise empty tty console).
Downgrading firmware-misc-nonfree to 20250808-1 fixes the problem. This
is why I'm confident that firmware-misc-nonfree is the culprit. Since
it's making the system unusable, I'm filing this bug with RC severity.

This bug affects the MNT Reform with Rockchip RK3588.

Thread in the community forum:
https://community.mnt.re/t/screen-remains-dark-after-booting/3940

First observed by user elb in IRC:
https://mntre.com/reform-irc-logs/2025-10-16.log.html#t21:28:51

I'll keep investigating but wanted to file this bug as RC before more
users upgrade and make their system unusable/hard to recover.

Thanks!

cheers, josch