https://bugs.freedesktop.org/show_bug.cgi?id=102468
--- Comment #2 from taijian@posteo.de --- I followed the recommendations of this page: https://wiki.archlinux.org/index.php/Hybrid_graphics
The call working on my system is: echo "\_SB.PCI0.PEG0.PEGP._OFF" > /proc/acpi/call
If I use this command on a system that does not have amdgpu blacklisted, however, this will lead to unstable system behaviour and a certain crash within ~5 min.