Created attachment 139673 [details]
dmesg with 4.18-wip 'vanilla-as-is'

OK, here come three dmesg outputs - first one is 'vanilla' drm-next-4.18-wip,
the second one is with the atpx quirk reversed, the third one is with the three
vga_switcheroo patches I mentioned in the original bug report reversed. That
third one is also the only one where my dGPU properly powers down.