[AMD] NVidia GPU output is only visible on HDMI

[wallefan]

Setup: 3070 Ti w/ Nvidia driver 515.57-9, Linux 5.18.14-arch1-1, AMD 6900HX with integrated Rembrandt [Radeon 680M] GPU. Internal monitor is connected to both (both show up as VGA controllers in lspci). HDMI output is only connected to the Nvidia card.

After doing a find-and-replace of intel with amd in /etc/X11/nvidia-xorg.conf, I can get a display output via HDMI with the Nvidia card. However, the internal monitor remains dark (unless I switch back to tty1, where the X session is at startup, at which point it comes back on and the HDMI monitor shows no signal). I suspect this is because something needs to happen, probably somewhere in sysfs, to tell the internal monitor to switch from the AMD input to the NVidia input. I have no idea where to even begin looking for how to accomplish this, so I'm going to open an issue, volunteer to test any potential solutions you find, and edit this if my aimless Googling takes me anywhere promising.