https://bugzilla.kernel.org/show_bug.cgi?id=65811
--- Comment #7 from Jack jack@cyphernaut.org --- running the kernel with radeon.runpm=0 allows me to successfully disable the discrete card with `echo OFF > /sys/kernel/debug/vgaswitcheroo/switch`
[root@localhost linux-git]# cat /sys/kernel/debug/vgaswitcheroo/switch 0:DIS: :Off:0000:01:00.0 1:IGD:+:Pwr:0000:00:02.0 [root@localhost linux-git]#
I should have more tests (and some logs) later this evening -- didn't have a clone of the kernel repo and 5mbps internet at the relatives makes for a lengthy download ;P