https://bugs.freedesktop.org/show_bug.cgi?id=73788
--- Comment #8 from Stepan Bakshaev step2back+freedesktop@gmail.com --- I installed kernel from here http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12-trusty/
and try to change power_method by http://xorg.freedesktop.org/wiki/RadeonFeature/#kmspowermanagementoptions
root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# uname -a Linux silverstone 3.12.0-031200-generic #201311071835 SMP Thu Nov 7 23:36:07 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# cat /proc/cmdline BOOT_IMAGE=/boot/vmlinuz-3.12.0-031200-generic root=UUID=4d025cce-1bf0-466f-a5c3-501d3f548e70 ro quiet splash vt.handoff=7 radeon.dpm=1
root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# echo "dynpm" > power_method bash: echo: write error: Invalid argument root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# echo "profile" > power_method bash: echo: write error: Invalid argument root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# cat power_method dpm
root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# echo "high"
power_profile
bash: echo: write error: Invalid argument root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# cat power_profile default
root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# dmesg | grep 'drm.*error'
root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# cat class 0x030000 root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# cat vendor 0x1002 root@silverstone:/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0# cat device 0x683d
There are no errors and no success in changing power_method. Where did I do mistake?