Kernel: 4.12.10-1-ARCH
Nvidia: 01:00.0 3D controller: NVIDIA Corporation GM108M [GeForce 940MX] (rev ff)
Driver: Nvidia 384.69

powertop --auto-tune makes Nvidia card not usable on battery

How to replicate:

1. Execute powertop --auto-tune OR echo 'auto' > '/sys/bus/pci/devices/0000:01:00.0/power/control';
2. unplug the power and run on battery
3. sudo tee /proc/acpi/bbswitch <<<ON and then cat /proc/acpi/bbswitch
4. Try to run any app with optirun ... fails

• This is what I see in dmesg:
  pci 0000:01:00.0: Refused to change power state, currently in D3
• Plug in the power again OR revert the PM setting (echo 'on' > '/sys/bus/pci/devices/0000:01:00.0/power/control';), don't solve the issue but I need to reboot the system:

Another user reported same issue here:
#140 (comment)