vgaswitcheroo doesn't work on 14.04 - discrete Radeon always on, Dell Vostro 3350
" saw in 13.10. The effect is exactly the same as if discrete graphics is on, laptop is loud and terribly overheats. Typing sudo echo OFF > /sys/kernel/debug/vgaswitcheroo/switch gives no effect, output of cat /sys/kernel/debug/vgaswitcheroo/switch doesn't change."
from my experience, DynOff works better than manual Off. It still says Off (DynOff) and I guess that it means the card is not powered and that this is automatic.
However, if you still want to roll things back to the manual settings, you have to modify grub. Use sudo to do the following:
open in any editor the file /etc/default/grub and find the line
GRUB_CMDLINE_LINUX_DEFAULT=
there should be values like "quiet splash" in this line; just add radeon.runpm=0 so it looks something like this:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash radeon.runpm=0"
save the file and run
sudo update-grub
then reboot. after rebooting, the behavior of cat /sys/kernel/debug/vgaswitcheroo/switch should be like in older ubuntu version. then you can run
echo OFF > /sys/kernel/debug/vgaswitheroo/switch
to see if it works - as you used to do before. if it works, add this line to /etc/rc.local just above exit 0.
i tried it on my machine and it basically works... but i think that DynOff is doing exactly the same. my computer is not overheating with both configurations.
Try this and confirm in comments if this works...
http://www.mostthingsweb.com/2014/07/disable-radeon-power-management-newer-linux-kernels/.
For me, during first reboot it gave a low graphics mode. Then, I pressed Ctrl+Alt+F2, and then ran the cat /sys/kernel/debug/vgaswitcheroo/switch, where it showed "Off" infront of DIS. Then, I ran sudo shutdown now -r to reboot. Finally,in the next reboot it worked. Also, I edited the etc/rc.local file to make this change permanent. Although I used Ubuntu 12.04.5, but I used the latest kernel 3.13...which, I believe, is the source of the problem, due to the recent changes in discrete graphics handling method.