https://bugzilla.kernel.org/show_bug.cgi?id=72701
--- Comment #10 from Alex Deucher alexdeucher@gmail.com --- Did manually powering on/off the dGPU via debugfs ever work on your system? See the "Forcing the power state of the devices" section of this page: http://nouveau.freedesktop.org/wiki/Optimus/ for how to test that.