Linux USB: turning the power on and off?

linux macos usb
Mark Harrison picture Mark Harrison · Jul 22, 2009 · Viewed 94.2k times · Source

How can I programmatically enable and disable the power to a particular USB port on Linux? Is such a thing even possible? Mac answers appreciated as well!

I was trying for a BOC (don't pretend you weren't try to get one too!) and ended up with one of these, and would like to get some use out of the thing by hooking it up to our server monitor.

Answer

mixonic picture mixonic · Jul 22, 2009

There is a sys entry for this in Linux. From Documentation/usb/power-management.txt:

power/level

This file contains one of three words: "on", "auto",
or "suspend".  You can write those words to the file
to change the device's setting.

"on" means that the device should be resumed and
autosuspend is not allowed.  (Of course, system
suspends are still allowed.)

"auto" is the normal state in which the kernel is
allowed to autosuspend and autoresume the device.

"suspend" means that the device should remain
suspended, and autoresume is not allowed.  (But remote
wakeup may still be allowed, since it is controlled
separately by the power/wakeup attribute.)

Something like: echo on > /sys/bus/usb/devices/usb5/power/level

You may need to play with the autosuspend setting as well. Without telling the kernel to stop trying, it may suspend the port automatically.

Good luck!

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