Comment 8 for bug 1814938

Running into the same problem. I have 2 Acer G6 G276HL (EDID: ACR Model 768) 27 inch monitors - one of them somehow got its EDID corrupted recently. Ideally, I'd like to write the good EDID into the monitor with the corrupted EDID, but barring that (edid-rw didn't work for me - IO error), I'd like to boot the system with a good EDID. I have two systems - one of which it works perfectly on, the other not so much.

Good system: Ubuntu 21.10 - only had to add good edid to /usr/lib/firmware/edid/acer_monitor.bin and update the grub conf accordingly - everything works.

Bad system: Ubuntu 20.04 based system. Steps tried:
- added good edid to /usr/lib/firmware/edid/acer_monitor.bin
- updated initramfs using script above as reference

In the good system: cat /sys/class/drm/card*/edid shows the updated edid for the card, while for the bad system, I don't see an edid override. cat /proc/cmdline confirms the edid override is in place.

e.g. for 20.04 based system (bad):

# cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.13.0-30-generic root=UUID=f896afab-6f99-4478-a402-9d612972a5b5 ro drm.edid_firmware=DP1:ed
id/acer_monitor.bin quiet splash vt.handoff=7

# lsinitramfs /boot/initrd.img|grep edid
usr/lib/firmware/edid
usr/lib/firmware/edid/acer_monitor.bin

# cat /sys/class/drm/card0-DP-1/edid
... no overridden EDID ...