Linux EDID stuff to force DP output to stay enabled when monitor is off or maybe make a generic virtual display

edid_stuff.sh

# make nice place for edid files
sudo mkdir -p /usr/lib/firmware/edid

# find edid file for your monitor or maybe get one from the interweb
sudo find /sys | grep /edid$

# copy it to firmware
sudo cp one_of_the_results /usr/lib/firmware/edid/xyz1337.bin

# check to make sure it's not garbage I guess
edid-decode /usr/lib/firmware/edid/xyz1337.bin

# add edid file to be loaded in initramfs, varies by distro
# e.g. mkinitcpio on arch
sudo nano /etc/mkinitcpio.conf
# FILES=(/usr/lib/firmware/edid/xyz1337.bin)

# add kernel command line to load edid and force connector on, varies by boot loader
# e.g. systemd-boot on arch
sudo nano /boot/loader/entries/arch.conf
# options ...whatever... drm.edid_firmware=DP-1:edid/xyz1337.bin video=DP-1:e

# rebuild initramfs somehow
sudo mkinitcpio -P

# maybe check that your edid is now in the initramfs
lsinitcpio /boot/initramfs-linux.img | grep xyz1337.bin

# reboot, turn off your DP monitor, it should stay usable and streamable