Turning off power to usb port. Or turn off power to entire usb subsystem

Question

I have a usb lamp which I specifically bought in order to turn it off programmatically at a certain time, thus I need to remove the power to its usb port.

I believe I have a usb-hub at usb6. The lamp is connected to one of the ports in this hub:

#myhost$ lsusb 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 008 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
...
...
Bus 008 Device 006: ID 050d:0234 Belkin Components F5U234 USB 2.0 4-Port Hub

Here's what I've tried:

Two solutions are here, the first suggests:

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

but I get write error: Invalid argument when trying to write to /sys/bus/usb/devices/usb1/power/level:

$sudo bash -c 'echo disabled > /sys/bus/usb/devices/usb6/power/wakeup'
$echo suspend|sudo tee /sys/bus/usb/devices/usb6/power/level suspend
tee: /sys/bus/usb/devices/usb6/power/level: Invalid argument
$sudo bash -c 'echo suspend> /sys/bus/usb/devices/usb6/power/level'bash: line 0: echo: write error: Invalid argument

The second solution:

sudo bash -c 'echo 0 > /sys/bus/usb/devices/usb6/power/autosuspend_delay_ms; echo auto > /sys/bus/usb/devices/usb6/power/control'

which does turn off power to the usb-hub device.

I was also trying to follow this:

But the output of lsusb -t just hangs:

$lsusb -t
4-1:0.0: No such file or directory
4-1:0.1: No such file or directory
^C

Which prevents me from using this method to get the '2-1.1' part to this:

echo '2-1.1' > /sys/bus/usb/drivers/usb/unbind

Is there an alternative way of getting this information?

Alternatively, is there a way to shut off power to the entire usb subsystem? Something like modprobe -r usb_etc?

My kernel is:

$uname -r
3.2.0-4-amd64

Answer 1

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

It works only on hubs that support per-port power switching, but note that many modern motherboards have USB hubs that support this feature.

First off, your OS may already have uhubctl present in package repositories, refer to README for how to install it, but make sure you use most recent version (2.4.0 as of this writing).

If your OS does not have recent version of this package, you can install it from source as follows:

To compile:

git clone https://github.com/mvp/uhubctl
cd uhubctl
make

To install system-wide as /usr/sbin/uhubctl:

sudo make install

To list status of all hubs, their locations and ports that can be controlled by uhubctl:

sudo uhubctl

(you can avoid using sudo if you configure udev USB permissions).

To turn off power on port 5 of single compatible hub:

sudo uhubctl -a 0 -p 5

If you have more than one compatible hub connected, use -l to specify hub location to control it:

sudo uhubctl -a 0 -p 5 -l 3-1.2

To toggle power off then on:

sudo uhubctl -a 2 -p 5

Note that USB 3.0 hubs are also supported, and quite a few new USB 3.0 hubs actually work well.

Read more here.

Answer 2

See Controlling a USB power supply (on/off) with linux, short version, for newer kernels "suspend" does not work anymore:

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

But it doesn't literally cut the power: it signals the device to poweroff, and it's up to the device to implement power management and do the right thing.

You have a lot of details in the official documentation in the kernel, there it explains the various files in /sys/bus/usb/devices/.../power/ and how to manage the devices and ports.

For things that are not real USB devices (does your USB lamp show up in lsusb?) you might be out of luck, I have tried myself with an usb lamp and with a GPS logger that charges its battery and transfers data through USB that shows up as a cp210x USB-to-serial, and neither does poweroff. I can "disconnect" the GPS with echo '5-4.6' > /sys/bus/usb/drivers/usb/unbind and reconnect it with echo '5-4.6' > /sys/bus/usb/drivers/usb/bind but the battery charging light is always on.

But it seems that some hubs do it properly.