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I am trying to follow the instructions on Lesswatts, to enable usb autosuspend.
When I run powertop, it says, that I have a device (USB device 2-6 : 2.4G Multimedia Wireless Kit (Chicony)) that is running 100% of the time.

I don't use the wifi and indeed I've blacklisted the wifi driver, so I am pretty confident I don't need this device. So I set the idle timeout to 2 seconds and

echo auto > /sys/bus/usb/devices/2-6/power/level

works, but the device is still active. If I try

echo suspend > /sys/bus/usb/devices/2-6/power/level

then the bash prompt skips ten lines and stops, but the contents of the file is still auto

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The information on Lesswatts is a bit outdated: dmesg says "power/level is deprecated; use power/control instead" and we can't write "suspend" anymore, only "on" or "auto" (see I'm also searching for an answer to your question, because my USB ports are still powered when the PC is off, and I want to turn them off. – elmicha May 6 '11 at 14:51
A "Multimedia Wireless Kit" doesn't have anything to do with wifi -- it sounds more like some kind of a remote control, or a mini wireless keyboard. – Marius Gedminas Feb 19 '12 at 14:14
@daithib8 Did Dustin's answer solve your problem? Can you mark as answer if so to let me know I should award the bounty? Thanks. – William Feb 20 '12 at 19:40
@Marius you are right. it was a keyboard and Power top does recommends auto suspend for non-input devices. doh – daithib8 May 5 '12 at 18:02
up vote 6 down vote accepted

You'll need to echo '1' into each of a number of sys files as root.

You can do so like this:

for i in /sys/bus/usb/devices/*/power/autosuspend; do
  echo 1 | sudo tee $i

The number '1' means 'auto suspend after '1' second. You might use '2' here, if that's the behavior you want.

Alternatively, you can install and run the powernap utility, which installs a script at /etc/pm/power.d/usb_autosuspend that handles this for you automatically.

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Do you know anything about which values mean what? I seem to have 2 in all my "files" – joar Mar 26 '12 at 21:16
1 means device suspend within 1 sec, 2 means suspend after 2 secs, etc. -1 means that your device will not suspend. – shantanu Mar 27 '12 at 12:46
Thanks, @shantanu. I'll add that to my answer. – Dustin Kirkland Mar 27 '12 at 16:39

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