Controlling a USB power supply (on/off) with Linux

Question

Is it possible to turn on/off power supplies from USB manually with Linux?

There's this external USB cooling fan (the kind you use to cool yourself off, not the PC), and it would be nice to be able to control it from the terminal, because I want to position the fan somewhere far away.

I suppose this could also be useful for a variety of other things as well, because there's a lot of USB toys out there. Maybe air purifiers, etc. (I heard they don't really work though).

Let me recap for Linux >= 2.6.38: **The file** ``power/level`` **is deprecated now; use** ``power/control`` **instead**. (``power/wakeup`` is ok.) Furthermore, it accepts only "auto" and "on", not "suspend" any more. "auto" is smart enough, and if the power isn't turned off while idle, it's the device's fault. Anyway you can't turn the power off manually. For more, see [the answer below](http://stackoverflow.com/a/12675749/780703) by [tlwhitec](http://stackoverflow.com/users/921269/tlwhitec) and the kernel's doc: https://www.kernel.org/doc/Documentation/usb/power-management.txt — teika kazura, Jul 04 '13 at 06:51
Possible duplicate of http://stackoverflow.com/q/1163824/1967396 — Floris, Apr 13 '14 at 04:32
Does it require any special hardware? It is not quite clear from answers, — Vojtěch Dohnal, Jun 14 '16 at 04:47
@VojtěchDohnal See https://unix.stackexchange.com/a/321945/111181 — jarno, Feb 03 '22 at 22:48

score 66 · Accepted Answer · edited Dec 06 '17 at 14:08

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Note. The information in this answer is relevant for the older kernels (up to 2.6.32). See tlwhitec's answer for the information on the newer kernels.

# disable external wake-up; do this only once
echo disabled > /sys/bus/usb/devices/usb1/power/wakeup 

echo on > /sys/bus/usb/devices/usb1/power/level       # turn on
echo suspend > /sys/bus/usb/devices/usb1/power/level  # turn off

(You may need to change usb1 to usb n)

Source: Documentation/usb/power-management.txt.gz

edited Dec 06 '17 at 14:08

ItamarG3

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answered Jan 15 '11 at 21:42

Roman Cheplyaka

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Whoa, thanks for that. I was thinking I had to go through libUSB no matter what. Any idea how to get the names of the attached devices as well? – kamziro Jan 15 '11 at 21:56
According to this post, without special hardware it isn't possible? http://blog.andrew.net.au/2009/01/17 – NoBugs Dec 31 '11 at 21:09
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I'm getting permission denied error even if I use sudo! – Wally Jul 26 '14 at 07:52
This disables the usb port, but typically that will *not* stop power flowing to it. – psusi Dec 11 '14 at 14:26
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same for me " permission denied" even after using sudo – Raulp Mar 04 '15 at 12:03
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The permission is denied because a command in the form of `sudo foo > bar` is parsed as _direct the output to `bar`, then run `foo` using `sudo`_. The redirection fails because it happens before you get root access. The solution is to use `sudo sh -c 'echo disabled > /sys/bus/usb/devices/usb1/power/wakeup'`, and so on: gain root, run a new hell to perform a redirect, then output something into the redirected file descriptor. – dig May 12 '15 at 19:26
On Ubuntu 15.04, kernel 3.19.0-28-generic, echo 'auto' turned the power off. 'echo suspend' gave 'write error: Invalid argument'. echo disabled to wakeup worked. I'm able to cycle power on and off. My device directory was also more involved. '/sys/bus/usb/devices/usb1/1-13/power/(wakeup|level). For example, ftdi is found from /sys/bus/usb/drivers/ftdi_sio/(1-13:1.0) – rickfoosusa Sep 18 '15 at 15:34
Sorry if I'm raising the dead here, but when I run `echo suspend > /sys/bus/usb/devices/usb1/power/level` in a root shell (bash), I am given an error message: `bash: echo: write error: Invalid argument`. Not sure what this means exactly... Any ideas? – Levi Jan 27 '16 at 03:24
@Levi `suspend` also doesn't work for me either - while value `auto` and `autosuspend_delay_ms` seems to be responsible for disconnects due to power-saving. http://unix.stackexchange.com/a/166601/110101 – Martin Zeitler May 01 '16 at 16:35
Why should wake up be disabled? – user3578181 Dec 14 '16 at 21:31
@dig "Run a new hell" made me ROTFL ;-) – Astrinus Mar 09 '20 at 15:06
sudo sh -c 'echo disabled > /sys/bus/usb/devices/usb1/power/wakeup' sh: 1: cannot create /sys/bus/usb/devices/usb1/power/wakeup: Read-only file system – ante.sabo Sep 30 '21 at 11:57

score 65 · Answer 2 · answered Oct 01 '12 at 14:56

65

According to the docs, there were several changes to the USB power management from kernels 2.6.32, which seem to settle in 2.6.38. Now you'll need to wait for the device to become idle, which is governed by the particular device driver. The driver needs to support it, otherwise the device will never reach this state. Unluckily, now the user has no chance to force this. However, if you're lucky and your device can become idle, then to turn this off you need to:

echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend"
echo "auto" > "/sys/bus/usb/devices/usbX/power/level"

or, for kernels around 2.6.38 and above:

echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend_delay_ms"
echo "auto" > "/sys/bus/usb/devices/usbX/power/control"

This literally means, go suspend at the moment the device becomes idle.

So unless your fan is something "intelligent" that can be seen as a device and controlled by a driver, you probably won't have much luck on current kernels.

answered Oct 01 '12 at 14:56

tlwhitec

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It seems this will cause the USB device to continuously get powered off...(?) How should power be resumed by me, after this worked? My goal is to restart the device once, not to permanently change its suspension configuration. – matanster Aug 16 '13 at 17:27
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To **resume** a suspended device, you can disable again the "autosuspend" with `echo "on" > "/sys/bus/usb/devices/usbX/power/control"`, but I think you need to understand the original purpose. The autosuspend feature is here merely to enable idling devices to enter a low-power state (where it might appear turned off), only to be resumed later when it's needed, either by the host or some external event. That happens (or should happen) automatically. The port itself is actually never truly turned off. Really, do read the [docs](http://www.kernel.org/doc/Documentation/usb/power-management.txt) ;) – tlwhitec Sep 24 '13 at 10:01
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I can confirm it works with kernels > 3.10. Just have to be sure that the device "id" you are using is correct : `dmesg | grep "usb"` and use the number after "usb", for example: `usb 2-4.4: SerialNumber: A0848020` you will use: `/sys/bus/usb/devices/2-4.4/power/...`. Also, be sure that the device is not in use. I created a [script to simplify this process](https://raw.githubusercontent.com/lepe/scripts/master/ubs_power.sh) – lepe Apr 27 '16 at 03:07
Is there a way to save this configuration so that each time it's plugged in it won't change back to defaults? I have a device that I need to set power control to "on" in order for it to charge. – quickblueblur Jan 30 '19 at 19:19
@quickblueblur sounds like an [udev rule](http://reactivated.net/writing_udev_rules.html) to me. – tlwhitec Jan 31 '19 at 14:15
[It seems that `udev` has now been either **deprecated** or **subsumed** by `systemd`](https://en.wikipedia.org/wiki/Udev#History). The OP's question here is now almost 10 years old, and in that time, the solutions all seem to be "hit-or-miss" - sometimes they work, sometimes they don't. Why? At least part of the issue seems to be that the term "USB Standard" is an oxymoron. – Seamus Oct 02 '20 at 20:47
@Seamus I think udev is not going anywhere. The wiki article only covers firmware loading. Not that I'd watch what's happening around it, by I haven't heard of it having any substitute. As far as I can tell using udev on the latest Fedora is definitely still a thing. – tlwhitec Oct 04 '20 at 18:46
@lepe Does it work under VirtualBox? It looks like it does not. Is there a way to make it work under VirtualBox? – arda30 May 17 '22 at 13:03
@arda30 I can confirm your findings. I doubt `power` can be controlled under VirtualBox as harware is emulated (specially USB has special configuration under VirtualBox). You should create a separate question for that. Sorry I'm not that helpful. – lepe May 18 '22 at 01:57

Dominic Cerisano · Answer 3 · 2017-06-27T22:41:12.790

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PowerTOP from Intel allows you to toggle devices such as usb peripherals in real-time. These are called 'tunables'.

sudo apt install powertop
sudo powertop

Tab over to 'tunables'.
Scroll down to your device.
Hit enter to toggle power saving mode (Good/Bad)

Note that Bad means the device is always on. Toggling to Good will turn off the device after the preset inactive saving time (default is 2000ms).

See the PowerTOP docs for details on how to make these changes permanent.
It generates the config scripts for you (pretty much as described by other posters on this thread).

NOTE: These scripts do not affect USB pin power (which is always on).
These only send the driver protocol to activate and deactivate a device.

If you want to control pin power, you could use either a supported smart USB hub, or better yet a microcontroller.

edited Jun 27 '17 at 22:41

answered May 06 '16 at 05:54

Dominic Cerisano

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Awesome! :D I think this is the userfriendliest way to do it (although on low level it makes the same operations as outlined in the other answers.) Thank you, and may your answer reach the top ;) – Matyas May 09 '16 at 09:03
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Thanks for your answer. Where do I have to start digging to change the preset inactive saving time? – mikezter Dec 21 '16 at 11:55
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As mentioned by previous posters, kernel docs are here: http://kernel.org/doc/Documentation/usb/power-management.txt – Dominic Cerisano Mar 09 '17 at 21:17

score 30 · Answer 4 · answered Aug 07 '13 at 08:12

I have found these solutions that at least work for properly configured Terminus FE 1.1 USB hub chip:

1.To turn off power on all USB ports of a hub, you may unbind the hub from kernel using:

echo "1-4.4.4" > /sys/bus/usb/drivers/usb/unbind

to turn power back on - you may bind it back using

echo "1-4.4.4" > /sys/bus/usb/drivers/usb/bind

2.Switching power at each port individually is trickier: I was able to use hubpower to control each port - but it comes with a downside: hubpower first disconnects the usbdevfs wich causes all of the USB devices to disconect from system, at least on ubuntu:

usb_ioctl.ioctl_code = USBDEVFS_DISCONNECT;
rc = ioctl(fd, USBDEVFS_IOCTL, &usb_ioctl);

With this ioctl disabled I was able to switch off individual port power without detaching all devices - but the power goes back on immediately (probably due to kernel seeing an uninitialized device) which causes USB device just to do a "cold restart" which is what I generally wanted to do. My patched hubpower is here

The bind/unbind entries are confirmed to work on linux kernel 2.6.34, the ICH8 chipset, and Ubuntu 10.04. — user1357196, Aug 22 '13 at 16:10
bind/unbind doesn't poweroff the USB port regardless the chipset. The device still gets power... — themihai, Nov 08 '14 at 18:41
mouse laser is off, keyboard cant type, modem stops blinking - all good on my platform — eri, Sep 19 '16 at 01:17

mvp · Answer 5 · 2020-01-18T18:48:40.993

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You could use my tool uhubctl to control USB power per port for compatible USB hubs.

edited Jan 18 '20 at 18:48

answered Nov 08 '16 at 20:00

mvp

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fine tool on osx, but doesnt find any 'supported smart hub' on debian for me. – jitter Jan 07 '18 at 23:13
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On Linux, you need to either run it as root (under sudo), or to configure udev device permissions. It's also possible that your Linux host doesn't have compatible hubs connected. – mvp Jan 07 '18 at 23:15
it's a 'beagle bone green' btw. – jitter Jan 11 '18 at 01:55
I tried this on my computer's hub and the program show power is off for the port, but a LED of the connected device is still on. So apparently there is some power in the port anyway. (Version 2.1.0) – jarno Feb 06 '22 at 13:29
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@jarno, many USB hub manufacturers save few cents on adding power switches. This is why I am maintaining list of all hubs that actually do work properly at https://github.com/mvp/uhubctl – mvp Feb 07 '22 at 07:46
Works like a charm on Beaglebone Black. – Alexandr Zarubkin Apr 14 '22 at 13:04

score 7 · Answer 6 · edited Dec 02 '19 at 17:45

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I wanted to do this, and with my USB hardware I couldn't. I wrote a hacky way how to do it here:

http://pintant.cat/2012/05/12/power-off-usb-device/ .

In a short way: I used a USB relay to open/close the V_CC of another USB cable...

edited Dec 02 '19 at 17:45

Peter Mortensen

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answered May 20 '12 at 10:25

Carles

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F1Linux · Answer 7 · 2019-08-28T12:34:35.040

The reason why folks post questions such as this is due to the dreaded- indeed "EVIL"- USB Auto-Suspend "feature".

Auto suspend winds-down the power to an "idle" USB device and unless the device's driver supports this feature correctly, the device can become uncontactable. So powering a USB port on/off is a symptom of the problem, not the problem in itself.

I'll show you how to GLOBALLY disable auto-suspend, negating the need to manually toggle the USB ports on & off:

Short Answer:

You do NOT need to edit "autosuspend_delay_ms" individually: USB autosuspend can be disabled globally and PERSISTENTLY using the following commands:

sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT="/&usbcore.autosuspend=-1 /' /etc/default/grub

update-grub

systemctl reboot

An Ubuntu 18.04 screen-grab follows at the end of the "Long Answer" illustrating how my results were achieved.

Long Answer:

It's true that the USB Power Management Kernel Documentation states autosuspend is to be deprecated and in in its' place "autosuspend_delay_ms" used to disable USB autosuspend:

"In 2.6.38 the "autosuspend" file will be deprecated
and replaced by the "autosuspend_delay_ms" file."

HOWEVER my testing reveals that setting usbcore.autosuspend=-1 in /etc/default/grub as below can be used as a GLOBAL toggle for USB autosuspend functionality- you do NOT need to edit individual "autosuspend_delay_ms" files.

The same document linked above states a value of "0" is ENABLED and a negative value is DISABLED:

power/autosuspend_delay_ms

    <snip> 0 means to autosuspend
    as soon as the device becomes idle, and negative
    values mean never to autosuspend.  You can write a
    number to the file to change the autosuspend
    idle-delay time.

In the annotated Ubuntu 18.04 screen-grab below illustrating how my results were achieved (and reproducible), please remark the default is "0" (enabled) in autosuspend_delay_ms.

Then note that after ONLY setting usbcore.autosuspend=-1 in Grub, these values are now negative (disabled) after reboot. This will save me the bother of editing individual values and can now script disabling USB autosuspend.

Hope this makes disabling USB autosuspend a little easier and more scriptable-

score 5 · Answer 8 · edited Apr 12 '14 at 17:05

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echo '2-1' |sudo tee /sys/bus/usb/drivers/usb/unbind

works for ubuntu

edited Apr 12 '14 at 17:05

mustaccio

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answered Apr 12 '14 at 16:46

user3527264

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YOURS IS THE ONLY SOLUTION THAT WORKED ON MY CASE. I am using an acer make laptop 12.04LTS Ubuntu. – RicoRicochet Dec 12 '14 at 05:57
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Doesn't poweroff the device, only removes it from the device list. How can I poweroff the USB port? – rustyx Dec 20 '14 at 15:11
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This is also the only solution that worked for me for powering off a Wacom Intuos5 touch M tablet without unplugging it (on Fedora 28) – user1738984 Sep 11 '18 at 10:50

score 2 · Answer 9 · answered Nov 24 '16 at 02:55

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USB 5v power is always on (even when the computer is turned off, on some computers and on some ports.) You will probably need to program an Arduino with some sort of switch, and control it via Serial library from USB plugged in to the computer.

In other words, a combination of this switch tutorial and this tutorial on communicating via Serial libary to Arduino plugged in via USB.

answered Nov 24 '16 at 02:55

NoBugs

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On nearly all hardware, the power to the USB host port is supplied via a current-limited power switch IC (e.g. Texas Instruments TPS2001D). It's pretty common for these switches to be controllable from software. So long as both the hardware, and the USB host controller device driver includes support for the hardware, then it can be controlled from software. – Tim Small Dec 17 '20 at 15:29

score 2 · Answer 10 · answered Jul 17 '17 at 08:51

I had a problem when connecting my android phone, I couldn't charge my phone because the power switch on and then off ... PowerTop let me find this setting and was useful to fix the issue ( auto value was causing issue):

echo 'on' | sudo tee /sys/bus/usb/devices/1-1/power/control

Controlling a USB power supply (on/off) with Linux

10 Answers10

Short Answer:

Long Answer:

Linked