Getting HDMI output to work with switchable graphics on Arch Linux

Graphics / Linux Linux
7

Update:

Ok, so I thought about your first reply. It occurred to me I never actually installed the xf86-video-amdgpu drivers, only the mesa (modesetting) drivers.

What works

I can confirm that after installing the amdgpu drivers and rebooting with the nvidia-drm.modeset=1 kernel parameter, GNOME will start with joined screens by default.

What didn’t work
  1. I get strange behaviour when trying to use external monitor only. For some reason, this causes the screen to be very “choppy” and there’s an input lag of several seconds from mouse and keyboard.
  2. Also, trying to change screen settings using xrandr resulted in a less than desirable outcome. For example, setting xrandr --output eDP --primary --auto --output HDMI-1-0 --right-of eDP --auto resulted in a frozen output in the upper left quarter of the external monitor.

The good news is I can now, seemingly, use HDMI output with switchable graphics. However, there’s still the lag issue of using external monitor only, which I do not fully understand. Any idea what’s causing this?