How do you reset a USB device from the command line?

Save the following as usbreset.c

/* usbreset -- send a USB port reset to a USB device */

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>

#include <linux/usbdevice_fs.h>


int main(int argc, char **argv)
{
    const char *filename;
    int fd;
    int rc;

    if (argc != 2) {
        fprintf(stderr, "Usage: usbreset device-filename\n");
        return 1;
    }
    filename = argv[1];

    fd = open(filename, O_WRONLY);
    if (fd < 0) {
        perror("Error opening output file");
        return 1;
    }

    printf("Resetting USB device %s\n", filename);
    rc = ioctl(fd, USBDEVFS_RESET, 0);
    if (rc < 0) {
        perror("Error in ioctl");
        return 1;
    }
    printf("Reset successful\n");

    close(fd);
    return 0;
}

The run the following commands in terminal:

1. Compile the program:

   $ cc usbreset.c -o usbreset
   

2. Get the Bus and Device ID of the USB device you want to reset:

   $ lsusb  
   Bus 002 Device 003: ID 0fe9:9010 DVICO  
   

3. Make our compiled program executable:

   $ chmod +x usbreset
   

4. Execute the program with sudo privilege; make necessary substitution for <Bus> and <Device> ids as found by running the lsusb command:

   $ sudo ./usbreset /dev/bus/usb/002/003  
   

Source of above program: http://marc.info/?l=linux-usb&m=121459435621262&w=2

I haven't found myself in your specific circumstances before, so I'm not sure if it'll do enough, but the simplest way I've found to reset a USB device is this command: (No external apps necessary)

sudo sh -c "echo 0 > /sys/bus/usb/devices/1-4.6/authorized"
sudo sh -c "echo 1 > /sys/bus/usb/devices/1-4.6/authorized"

That's the actual one I use to reset my Kinect since libfreenect seems to have no API for putting it back to sleep. It's on my Gentoo box, but the kernel should be new enough to use the same path structure for sysfs.

Yours obviously wouldn't be 1-4.6 but you can either pull that device path from your kernel log (dmesg) or you can use something like lsusb to get the vendor and product IDs and then use a quick command like this to list how the paths relate to different vendor/product ID pairs:

for X in /sys/bus/usb/devices/*; do 
    echo "$X"
    cat "$X/idVendor" 2>/dev/null 
    cat "$X/idProduct" 2>/dev/null
    echo
done

This will reset all of USB1/2/3 attached ports[1]:

for i in /sys/bus/pci/drivers/[uoex]hci_hcd/*:*; do
  [ -e "$i" ] || continue
  echo "${i##*/}" > "${i%/*}/unbind"
  echo "${i##*/}" > "${i%/*}/bind"
done

I believe this will solve your problem. If you do not want to reset all of the USB endpoints, you can use appropriate device ID from /sys/bus/pci/drivers/ehci_hcd

Notes: [1]: the *hci_hcd kernel drivers typically control the USB ports. ohci_hcd and uhci_hcd are for USB1.1 ports, ehci_hcd is for USB2 ports and xhci_hcd is for USB3 ports. (see https://en.wikipedia.org/wiki/Host_controller_interface_(USB,_Firewire))

I've created a Python script that simplifies the whole process based on answers here.

Save the script below as reset_usb.py or clone this repo.

Usage:

python reset_usb.py help  # Show this help
sudo python reset_usb.py list  # List all USB devices
sudo python reset_usb.py path /dev/bus/usb/XXX/YYY  # Reset USB device using path /dev/bus/usb/XXX/YYY
sudo python reset_usb.py search "search terms"  # Search for USB device using the search terms within the search string returned by list and reset matching device
sudo python reset_usb.py listpci  # List all PCI USB devices
sudo python reset_usb.py pathpci /sys/bus/pci/drivers/.../XXXX:XX:XX.X  # Reset PCI USB device using path /sys/bus/pci/drivers/.../XXXX:XX:XX.X
sudo python reset_usb.py searchpci "search terms"  # Search for PCI USB device using the search terms within the search string returned by listpci and reset matching device

Script:

#!/usr/bin/env python
import os
import sys
from subprocess import Popen, PIPE
import fcntl

instructions = '''
Usage: python reset_usb.py help : Show this help
       sudo python reset_usb.py list : List all USB devices
       sudo python reset_usb.py path /dev/bus/usb/XXX/YYY : Reset USB device using path /dev/bus/usb/XXX/YYY
       sudo python reset_usb.py search "search terms" : Search for USB device using the search terms within the search string returned by list and reset matching device
       sudo python reset_usb.py listpci : List all PCI USB devices
       sudo python reset_usb.py pathpci /sys/bus/pci/drivers/.../XXXX:XX:XX.X : Reset PCI USB device using path
       sudo python reset_usb.py searchpci "search terms" : Search for PCI USB device using the search terms within the search string returned by listpci and reset matching device       
       '''


if len(sys.argv) < 2:
    print(instructions)
    sys.exit(0)

option = sys.argv[1].lower()
if 'help' in option:
    print(instructions)
    sys.exit(0)


def create_pci_list():
    pci_usb_list = list()
    try:
        lspci_out = Popen('lspci -Dvmm', shell=True, bufsize=64, stdin=PIPE, stdout=PIPE, close_fds=True).stdout.read().strip().decode('utf-8')
        pci_devices = lspci_out.split('%s%s' % (os.linesep, os.linesep))
        for pci_device in pci_devices:
            device_dict = dict()
            categories = pci_device.split(os.linesep)
            for category in categories:
                key, value = category.split('\t')
                device_dict[key[:-1]] = value.strip()
            if 'USB' not in device_dict['Class']:
                continue
            for root, dirs, files in os.walk('/sys/bus/pci/drivers/'):
                slot = device_dict['Slot']
                if slot in dirs:
                    device_dict['path'] = os.path.join(root, slot)
                    break
            pci_usb_list.append(device_dict)
    except Exception as ex:
        print('Failed to list pci devices! Error: %s' % ex)
        sys.exit(-1)
    return pci_usb_list


def create_usb_list():
    device_list = list()
    try:
        lsusb_out = Popen('lsusb -v', shell=True, bufsize=64, stdin=PIPE, stdout=PIPE, close_fds=True).stdout.read().strip().decode('utf-8')
        usb_devices = lsusb_out.split('%s%s' % (os.linesep, os.linesep))
        for device_categories in usb_devices:
            if not device_categories:
                continue
            categories = device_categories.split(os.linesep)
            device_stuff = categories[0].strip().split()
            bus = device_stuff[1]
            device = device_stuff[3][:-1]
            device_dict = {'bus': bus, 'device': device}
            device_info = ' '.join(device_stuff[6:])
            device_dict['description'] = device_info
            for category in categories:
                if not category:
                    continue
                categoryinfo = category.strip().split()
                if categoryinfo[0] == 'iManufacturer':
                    manufacturer_info = ' '.join(categoryinfo[2:])
                    device_dict['manufacturer'] = manufacturer_info
                if categoryinfo[0] == 'iProduct':
                    device_info = ' '.join(categoryinfo[2:])
                    device_dict['device'] = device_info
            path = '/dev/bus/usb/%s/%s' % (bus, device)
            device_dict['path'] = path

            device_list.append(device_dict)
    except Exception as ex:
        print('Failed to list usb devices! Error: %s' % ex)
        sys.exit(-1)
    return device_list


if 'listpci' in option:
    pci_usb_list = create_pci_list()
    for device in pci_usb_list:
        print('path=%s' % device['path'])
        print('    manufacturer=%s' % device['SVendor'])
        print('    device=%s' % device['SDevice'])
        print('    search string=%s %s' % (device['SVendor'], device['SDevice']))
    sys.exit(0)

if 'list' in option:
    usb_list = create_usb_list()
    for device in usb_list:
        print('path=%s' % device['path'])
        print('    description=%s' % device['description'])
        print('    manufacturer=%s' % device['manufacturer'])
        print('    device=%s' % device['device'])
        print('    search string=%s %s %s' % (device['description'], device['manufacturer'], device['device']))
    sys.exit(0)

if len(sys.argv) < 3:
    print(instructions)
    sys.exit(0)

option2 = sys.argv[2]

print('Resetting device: %s' % option2)


# echo -n "0000:39:00.0" | tee /sys/bus/pci/drivers/xhci_hcd/unbind;echo -n "0000:39:00.0" | tee /sys/bus/pci/drivers/xhci_hcd/bind
def reset_pci_usb_device(dev_path):
    folder, slot = os.path.split(dev_path)
    try:
        fp = open(os.path.join(folder, 'unbind'), 'wt')
        fp.write(slot)
        fp.close()
        fp = open(os.path.join(folder, 'bind'), 'wt')
        fp.write(slot)
        fp.close()
        print('Successfully reset %s' % dev_path)
        sys.exit(0)
    except Exception as ex:
        print('Failed to reset device! Error: %s' % ex)
        sys.exit(-1)


if 'pathpci' in option:
    reset_pci_usb_device(option2)


if 'searchpci' in option:
    pci_usb_list = create_pci_list()
    for device in pci_usb_list:
        text = '%s %s' % (device['SVendor'], device['SDevice'])
        if option2 in text:
            reset_pci_usb_device(device['path'])
    print('Failed to find device!')
    sys.exit(-1)


def reset_usb_device(dev_path):
    USBDEVFS_RESET = 21780
    try:
        f = open(dev_path, 'w', os.O_WRONLY)
        fcntl.ioctl(f, USBDEVFS_RESET, 0)
        print('Successfully reset %s' % dev_path)
        sys.exit(0)
    except Exception as ex:
        print('Failed to reset device! Error: %s' % ex)
        sys.exit(-1)


if 'path' in option:
    reset_usb_device(option2)


if 'search' in option:
    usb_list = create_usb_list()
    for device in usb_list:
        text = '%s %s %s' % (device['description'], device['manufacturer'], device['device'])
        if option2 in text:
            reset_usb_device(device['path'])
    print('Failed to find device!')
    sys.exit(-1)

I needed to automate this in a python script, so I adapted LiLo's extremely helpful answer to the following:

#!/usr/bin/env python
import os
import sys
from subprocess import Popen, PIPE
import fcntl
driver = sys.argv[-1]
print "resetting driver:", driver
USBDEVFS_RESET= 21780

try:
    lsusb_out = Popen("lsusb | grep -i %s"%driver, shell=True, bufsize=64, stdin=PIPE, stdout=PIPE, close_fds=True).stdout.read().strip().split()
    bus = lsusb_out[1]
    device = lsusb_out[3][:-1]
    f = open("/dev/bus/usb/%s/%s"%(bus, device), 'w', os.O_WRONLY)
    fcntl.ioctl(f, USBDEVFS_RESET, 0)
except Exception, msg:
    print "failed to reset device:", msg

In my case it was the cp210x driver (which I could tell from lsmod | grep usbserial), so you could save the above snippet as reset_usb.py and then do this:

sudo python reset_usb.py cp210x

This might also be helpful if you don't already have a c compiler setup on your system, but you do have python.

Since the APT package usbutils provides the usbreset binary you can just reset the USB device by:

usbreset ${USB_ID}

e.g.
usbreset 0d8c:0102

I'm using kind of sledgehammer by reloading the modules. This is my usb_reset.sh script:

#!/bin/bash

# USB drivers
rmmod xhci_pci
rmmod ehci_pci

# uncomment if you have firewire
#rmmod ohci_pci

modprobe xhci_pci
modprobe ehci_pci

# uncomment if you have firewire
#modprobe ohci_pci

And this is my systemd service file /usr/lib/systemd/system/usbreset.service which runs usb_reset.sh after my diplay manager has started:

[Unit]
Description=usbreset Service
After=gdm.service
Wants=gdm.service

[Service]
Type=oneshot
ExecStart=/path/to/usb_reset.sh

Quickest way to reset will be to reset the USB controller itself. Doing so will enforce udev to unregister the device on disconnection, and register is back once you enable it.

echo -n "0000:00:1a.0" | tee /sys/bus/pci/drivers/ehci_hcd/unbind
echo -n "0000:00:1d.0" | tee /sys/bus/pci/drivers/ehci_hcd/unbind
echo -n "0000:00:1a.0" | tee /sys/bus/pci/drivers/ehci_hcd/bind
echo -n "0000:00:1d.0" | tee /sys/bus/pci/drivers/ehci_hcd/bind

This should work for most PC environment. However, if you are using some custom hardware you can simply iterate through the device names. With this method you don't need to find out the device name by lsusb. You can incorporate in a automated script as well.

As the special case of the question is a communication problem of gphoto2 with a camera on USB, there is an option in gphoto2 to reset its USB connection:

gphoto2 --reset

Maybe this option didn't exist in 2010 when the question was asked.

I made a python script which will reset a particular USB device based on the device number. You can find out the device number from command lsusb.

for example:

$ lsusb

Bus 002 Device 004: ID 046d:c312 Logitech, Inc. DeLuxe 250 Keyboard

In this string 004 is the device number

import os
import argparse
import subprocess

path='/sys/bus/usb/devices/'

def runbash(cmd):
    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
    out = p.stdout.read().strip()
    return out

def reset_device(dev_num):
    sub_dirs = []
    for root, dirs, files in os.walk(path):
            for name in dirs:
                    sub_dirs.append(os.path.join(root, name))

    dev_found = 0
    for sub_dir in sub_dirs:
            if True == os.path.isfile(sub_dir+'/devnum'):
                    fd = open(sub_dir+'/devnum','r')
                    line = fd.readline()
                    if int(dev_num) == int(line):
                            print ('Your device is at: '+sub_dir)
                            dev_found = 1
                            break

                    fd.close()

    if dev_found == 1:
            reset_file = sub_dir+'/authorized'
            runbash('echo 0 > '+reset_file) 
            runbash('echo 1 > '+reset_file) 
            print ('Device reset successful')

    else:
            print ("No such device")

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('-d', '--devnum', dest='devnum')
    args = parser.parse_args()

    if args.devnum is None:
            print('Usage:usb_reset.py -d <device_number> \nThe device    number can be obtained from lsusb command result')
            return

    reset_device(args.devnum)

if __name__=='__main__':
    main()