uhubctl

uhubctl is utility to control USB power per-port on smart USB hubs. Smart hub is defined as one that implements per-port power switching.

Original idea for this code was inspired by hub-ctrl.c by Niibe Yutaka: https://www.gniibe.org/development/ac-power-control-by-USB-hub

Compatible USB hubs

Note that very few hubs actually support per-port power switching. Some of them are no longer manufactured and can be hard to find.

This is list of known compatible USB hubs:

This table is by no means complete. If your hub works with uhubctl, but is not listed above, please report it by opening new issue at https://github.com/mvp/uhubctl/issues, so we can add it to supported table. In your report, please provide exact product model and add output from uhubctl and please test VBUS off support as described below in FAQ.

Note that quite a few modern motherboards have built-in root hubs that do support this feature - you may not even need to buy any external hub.

USB 3.0 duality note

If you have USB 3.0 hub connected to USB3 upstream port, it will be detected as 2 independent virtual hubs: USB2 and USB3, and your USB devices will be connected to USB2 or USB3 virtual hub depending on their capabilities and connection speed. To control power for such hubs, it is necessary to turn off/on power on both USB2 and USB3 virtual hubs for power off/on changes to take effect. uhubctl will try to do this automatically (unless you disable this behavior with option -e).

Unfortunately, while most hubs will cut off data USB connection, some may still not cut off VBUS to port, which means connected phone may still continue to charge from port that is powered off by uhubctl.

Compiling

This utility was tested to compile and work on Linux (Ubuntu/Debian, Redhat/Fedora/CentOS, Arch Linux, Gentoo, openSUSE, Buildroot), FreeBSD, NetBSD, SunOS and MacOS.

⚠️ MacOS 12.4 x86 has USB stack bug which breaks uhubctl operation. Solution is to upgrade to MacOS 12.5 which has this bug fixed.

While uhubctl compiles on Windows, USB power switching does not work on Windows because libusb is using winusb.sys driver, which according to Microsoft does not support necessary USB control requests. This may be fixed if libusb starts supporting different driver on Windows.

Note that it is highly recommended to have pkg-config installed (many platforms provide it by default).

First, you need to install library libusb-1.0 (version 1.0.12 or later, 1.0.16 or later is recommended):

• Ubuntu: sudo apt-get install libusb-1.0-0-dev
• Redhat: sudo yum install libusb1-devel
• MacOS: brew install libusb, or sudo port install libusb-devel
• FreeBSD: libusb is included by default
• NetBSD: sudo pkgin install libusb1 gmake pkg-config
• Windows: TBD?

To fetch uhubctl source and compile it:

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

This should generate uhubctl binary. You can install it in your system as /usr/sbin/uhubctl using:

sudo make install

Note that on some OS (e.g. FreeBSD/NetBSD) you need to use gmake instead to build.

Also, on MacOS you can install uhubctl with all necessary dependencies in one shot using Homebrew tap:

brew tap mvp/uhubctl https://github.com/mvp/uhubctl
brew install uhubctl

To build/install from master branch, use --HEAD:

brew install uhubctl --HEAD

Usage

⚠️ On Linux, use sudo or configure USB permissions as described below!

To list all supported hubs:

uhubctl

You can control the power on a USB port(s) like this:

uhubctl -a off -p 2

This means operate on default smart hub and turn power off (-a off, or -a 0) on port 2 (-p 2). Supported actions are off/on/cycle/toggle (or 0/1/2/3). cycle means turn power off, wait some delay (configurable with -d) and turn it back on. Ports can be comma separated list, and may use - for ranges e.g. 2, or 2,4, or 2-5, or 1-2,5-8.

⚠️ Turning off built-in USB ports may cut off your keyboard or mouse, so be careful which ports you are turning off!

If you have more than one smart USB hub connected, you should choose specific hub to control using -l (location) parameter. To find hub locations, simply run uhubctl without any parameters. Hub locations look like b-x.y.z, where b is USB bus number, and x, y, z... are port numbers for all hubs in chain, starting from root hub for a given USB bus. This address is semi-stable - it will not change if you unplug/replug (or turn off/on) USB device into the same physical USB port (this method is also used in Linux kernel).

Linux USB permissions

On Linux, you should configure udev USB permissions (otherwise you will have to run it as root using sudo uhubctl).

Starting with Linux Kernel 6.0 there is a standard interface to turn USB hub ports on or off, and uhubctl will try to use it (instead of libusb) to set the port status. This is why there are additional rules for 6.0+ kernels. There is no harm in having these rules on systems running older kernel versions.

To fix USB permissions, first run sudo uhubctl and note all vid:pid for hubs you need to control. Then, add udev rules like below to file /etc/udev/rules.d/52-usb.rules (replace 2001 with your hub vendor id, or completely remove ATTR{idVendor} filter to allow any USB hub access):

SUBSYSTEM=="usb", DRIVER=="usb", MODE="0666", ATTR{idVendor}=="2001"
# Linux 6.0 or later (its ok to have this block present for older Linux kernels):
SUBSYSTEM=="usb", DRIVER=="usb", \
  RUN="/bin/sh -c \"chmod -f 666 $sys$devpath/*-port*/disable || true\""

Note that for USB3 hubs, some hubs use different vendor ID for USB2 vs USB3 components of the same chip, and both need permissions to make uhubctl work properly. E.g. for Raspberry Pi 4B, you need to add these 2 lines (or remove idVendor filter):

SUBSYSTEM=="usb", DRIVER=="usb", MODE="0666", ATTR{idVendor}=="2109"
SUBSYSTEM=="usb", DRIVER=="usb", MODE="0666", ATTR{idVendor}=="1d6b"

If you don't like wide open mode 0666, you can restrict access by group like this:

SUBSYSTEM=="usb", DRIVER=="usb", MODE="0664", GROUP="dialout"
# Linux 6.0 or later (its ok to have this block present for older Linux kernels):
SUBSYSTEM=="usb", DRIVER=="usb", \
  RUN+="/bin/sh -c \"chown -f root:dialout $sys$devpath/*-port*/disable || true\"" \
  RUN+="/bin/sh -c \"chmod -f 660 $sys$devpath/*-port*/disable || true\""

and then add permitted users to dialout group:

sudo usermod -a -G dialout $USER

For your udev rule changes to take effect, reboot or run:

sudo udevadm trigger --attr-match=subsystem=usb

For your convenience, ready to use udev rule is provided here.

FAQ

What is USB per-port power switching?

According to USB 2.0 specification, USB hubs can advertise no power switching, ganged (all ports at once) power switching or per-port (individual) power switching. Note that by default uhubctl will only detect USB hubs which support per-port power switching (but you can force it to try operating on unsupported hubs with option -f). You can find what kind of power switching your hardware supports by using sudo lsusb -v:

No power switching:

wHubCharacteristic 0x000a
  No power switching (usb 1.0)
  Per-port overcurrent protection

Ganged power switching:

wHubCharacteristic 0x0008
  Ganged power switching
  Per-port overcurrent protection

Per-port power switching:

wHubCharacteristic 0x0009
  Per-port power switching
  Per-port overcurrent protection

How do I check if my USB hub is supported by uhubctl?

1. Run sudo uhubctl. If your hub is not listed, it is not supported. Alternatively, you can run sudo lsusb -v and check for Per-port power switching - if you cannot see such line in lsusb output, hub is not supported.
2. Check for VBUS (voltage) off support: plug a phone, USB light or USB fan into USB port of your hub. Try using uhubctl to turn power off on that port, and check that phone stops charging, USB light stops shining or USB fan stops spinning. If VBUS doesn't turn off, your hub manufacturer did not include circuitry to actually cut power off. Such hub would still work to cut off USB data connection, but it cannot turn off power, and we do not consider this supported device.
3. If tests above were successful, please report your hub by opening new issue at https://github.com/mvp/uhubctl/issues, so we can add it to list of supported devices. Please do not report unsupported hubs, unless it is different hardware revision of some already listed supported model.

USB devices are not removed after port power down on Linux

➡️ This is fixed by #450 if you are using Linux kernel 6.0 or later.

After powering down USB port, udev does not get any event, so it keeps the device files around. However, trying to access the device files will lead to an IO error.

This is Linux kernel issue. It may be eventually fixed in kernel, see more discussion here. Basically what happens here is that kernel USB driver knows about power off, but doesn't send notification about it to udev.

You can use this workaround for this issue:

sudo uhubctl -a off -l ${location} -p ${port}
sudo udevadm trigger --action=remove /sys/bus/usb/devices/${location}.${port}/

Device file will be removed by udev, but USB device will be still visible in lsusb. Note that path /sys/bus/usb/devices/${location}.${port} will only exist if device was detected on that port. When you turn power back on, device should re-enumerate properly (no need to call udevadm again).

Power comes back on after few seconds on Linux

➡️ This is fixed by #450 if you are using Linux kernel 6.0 or later.

Some device drivers in kernel are surprised by USB device being turned off and automatically try to power it back on.

You can use option -r N where N is some number from 10 to 1000 to fix this - uhubctl will try to turn power off many times in quick succession, and it should suppress that. This may be eventually fixed in kernel, see more discussion here.

Disabling USB authorization for device in question before turning power off with uhubctl should help:

echo 0 > sudo tee /sys/bus/usb/devices/${location}.${port}/authorized

If your device is USB mass storage, invoking udisksctl before calling uhubctl should help too:

sudo udisksctl power-off --block-device /dev/disk/...`
sudo uhubctl -a off ...

Multiple 4-port hubs are detected, but I only have one 7-port hub connected

Many hub manufacturers build their USB hubs using basic 4 port USB chips. E.g. to make 7 port hub, they daisy-chain two 4 port hubs - 1 port is lost to daisy-chaining, so it makes it 4+4-1=7 port hub. Similarly, 10 port hub could be built as 3 4-port hubs daisy-chained together, which gives 4+4+4-2=10 usable ports.

Note that you should never try to change power state for ports used to daisy-chain internal hubs together. Doing so will confuse internal hub circuitry and will cause unpredictable behavior.

Raspberry Pi turns power off on all ports, not just the one I specified

This is the limitation of Raspberry Pi hardware design. As a workaround, you can buy any external USB hub from supported list above, attach it to any USB port of Raspberry Pi, and control power on its ports independently. Also, there are supported hubs designed specifically for Raspberry Pi, e.g. UUGear MEGA4.

For reference, supported Raspberry Pi models have following internal USB topology:

Raspberry Pi B+,2B,3B

• Single hub 1-1, ports 2-5 ganged, all controlled by port 2:

  uhubctl -l 1-1 -p 2 -a 0
  

  Trying to control ports 3,4,5 will not do anything. Port 1 controls power for Ethernet+WiFi.

Raspberry Pi 3B+

• Main hub 1-1, all 4 ports ganged, all controlled by port 2 (turns off secondary hub ports as well). Port 1 connects hub 1-1.1 below, ports 2 and 3 are wired outside, port 4 not wired.

  uhubctl -l 1-1 -p 2 -a 0
  

• Secondary hub 1-1.1 (daisy-chained to main): 3 ports, port 1 is used for Ethernet+WiFi, and ports 2 and 3 are wired outside.

Raspberry Pi 4B

⚠️ If your VL805 firmware is older than 00137ad (check with sudo rpi-eeprom-update), you have to update firmware to make power switching work on RPi 4B.

• USB2 hub 1, 1 port, only connects hub 1-1 below.

• USB2 hub 1-1, 4 ports ganged, dual to USB3 hub 2 below:

  uhubctl -l 1-1 -a 0
  

• USB3 hub 2, 4 ports ganged, dual to USB2 hub 1-1 above:

  uhubctl -l 2 -a 0
  

• USB2 hub 3, 1 port, OTG controller. Power switching is not supported.

Notable projects using uhubctl

Copyright

Copyright (C) 2009-2023 Vadim Mikhailov

This file can be distributed under the terms and conditions of the GNU General Public License version 2.