Got it working. Had to edit the edid file on a different pc because the changes wouldn’t be saved by wxedid locally. Not even with sudo. Opening the file from another location on the disk after making a copy did not work either. Basically it comes down to this:
- locate the edid file on the machine. (somewhere in subdir of /sys/devices/pci0000:00)
- make a copy and edit it with wxedit (aur), apply Ignore EDID Errors under options…
- in my case it involved the file under card0-HDMI-A-1. (use search function in file manager to make it easier)
- Find SPF: Supported features → vsig_format → replace 0b01 wih 0b00
- options> assemble EDID. Save binary and overwrite.
- Find CHD: CEA-861 header → change the value of YCbCr420 and YCbCr444 to 0
- options> assemble EDID. Save binary and overwrite.
- place file in usr/lib/firmware/edid, create a dir when absent:
sudo mkdir /lib/firmware/edid
- modify grub file by adding to GRUB_CMDLINE_LINUX_DEFAULT :
drm.edid_firmware=HDMI-A-1:edid/XB270HU.bin video=HDMI-A-1
- save grub file.
Note: Replace DP-3:e with your system specific setup.
And finally update grub:
sudo update-grub