nvidia-prime is no longer able to turn off the discrete GPU

[Mar-castelluccio]

Since updating to Ubuntu 18.04 from 17.10, the discrete GPU is no longer turned off.

I see since https://bugs.launchpad.net/ubuntu/+source/nvidia-prime/+bug/1757180 the way to turn off the discrete GPU has been changed, I suppose that's what caused the regression.

My laptop is a ThinkPad W541, with a NVIDIA Quadro K2100M.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Tom (tom-lorinthe)]

With this GRUB in /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT="nouveau.modeset=0"

And script:

#!/bin/bash
echo "Switching off nvidia"
# move from Nvidia to intel graphics (if not already done)
prime-select intel
# switch of power to Nvidia (repeat after each laptop start)
echo "auto" > /sys/bus/pci/devices/0000\:01\:00.0/power/control

It Nvidia powers down on my Dell XPS15 9560