Disabling dGPU on Dell XPS 9560 on Ubuntu 16.10

disable-dgpu-xps9560-ubuntu-1610

# Tested with kernel: 4.9.20-040920-generic

#
# Make sure to install following packages
#
sudo apt install acpi acpi-call-dkms

#
# To manually disable, you can run the following command
#
echo '\_SB.PCI0.PEG0.PEGP._OFF' > /proc/acpi/call            # via root
echo '\_SB.PCI0.PEG0.PEGP._OFF' | sudo tee /proc/acpi/call    # via your own user

#
# To automate on startup, do the following: 
#
echo acpi_call > /etc/modules-load.d/acpi_call.conf

# Create /usr/lib/systemd/user/dgpu-off.service with the following contents:
  [Unit]
  Description=Power-off dGPU
  After=graphical.target

  [Service]
  Type=oneshot
  ExecStart=/bin/sh -c "echo '\\_SB.PCI0.PEG0.PEGP._OFF' > /proc/acpi/call"

  [Install]
  WantedBy=graphical.target

# Enable the new unit file
systemctl enable /usr/lib/systemd/user/dgpu-off.service

@htrex glad to be of help!

I am not entirely sure why you get the not called response after (re)boot though. I have the same response btw. I know that I tested this by also adding the cat /proc/acpi/call cmd to the ExecStart line of the unit file. After reboot I checked the output with journalctl -u dgpu-off and it showed me 0x0called. I don't think I ever actually did a manual cat, but I did add it in the Gist as a check... I'll remove it as it only confuses.

Btw what I noticed is that when you do cat on /proc/acpi/call for a second time it will also give a not called response, perhaps a similar system call is being done on it after the systemd initialization. But I'm just speculating :)

@jseris Thanks for sharing! Much cleaner solution than what I had been using.

@jseris I think this line https://gist.github.com/jseris/a740f6a3fb0d18064e26dc66f9be4f1d#file-disable-dgpu-xps9560-ubuntu-1610-L12 should have \ in front missing

@quentin-sommer you are correct, I have updated the gist with your correction. Thanks 👍

@jseris first off, thanks a ton for writing this up - very useful for those who don't want to use bumblebee but still want to disable the GPU. I can confirm that this also works for Ubuntu 16.04.4. There is just one thing left, for some reason when I boot up I get stuck at a black screen unless I add the following kernel parameter nouveau.modeset=0. Since I have blacklisted the module I don't understand why this would still be necessary (and would of course prefer to avoid doing this). Any advice/pointers are appreciated.