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Every now and then there might come a need to reset a USB device, is there a way to perform the reset in software without unplugging the device itself and then pluggin it back in?

More specifically I have a webcam which gets confused when playing too much with the settings in guvcapture and then needs a reset to get back on track.

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4 Answers 4

Reset to default
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You could try Benjamin Close's resetusb program to reset all devices — there are no binaries available, but compiling it is rather easy. Save the source code as resetusb.c, then run:

gcc -lusb resetusb.c -o resetusb

You can now run the tool as resetusb. Alternatively, @unhammer points to Alan Stern's single-device version (plus some hints on how to use it).

Some people have also had luck just removing and modprobe-ing the relevant modules:

modprobe -vr ehci_hcd
modprobe -v ehci_hcd

(you could of course script this)

Some distributions may also have their own tools to restart the USB subsystem; Mandrake apparently has /etc/init.d/usb.

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  • askubuntu.com/questions/645/… has a similar program for resetting a single usb device
    – unhammer
    Dec 31, 2013 at 14:34
  • $ sudo modprobe -vr ehci_hcd results in modprobe: FATAL: Module ehci_hcd is builtin. on kubuntu trusty.
    – naught101
    Jun 28, 2014 at 3:42
  • On my laptop with debian 8, ehci_hcd gives errors. However, rmmod ehci_pci && sleep 2 && modprobe ehci_pci works perfectly.
    – Bharat G
    Oct 12, 2015 at 14:16
  • The modprobe trick did the job on CentOS 4 :-( , saved my day !
    – Open SEO
    Jun 9, 2016 at 13:09
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Let's say I want to reset /dev/sdc.

# udevadm info -q all /dev/sdc | grep DEVPATH
E: DEVPATH=/devices/pci0000:00/0000:00:14.0/usb2/2-1/2-1.4/2-1.4:1.0/host2/target2:0:0/2:0:0:0/block/sdc

I take the 2-1.4 above (yours might just be 2-1 - my device is plugged into a hub) and do:

# echo 2-1.4 > /sys/bus/usb/drivers/usb/unbind
# echo 2-1.4 > /sys/bus/usb/drivers/usb/bind
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    I've made a one-liner(-ish) for that: DEV="sdc"; USB=$(udevadm info -q all /dev/$DEV | grep DEVPATH | grep -o '/usb[1-9]*/[1-9,-]*' | cut -d'/' -f3); echo $USB > /sys/bus/usb/drivers/usb/unbind; echo $USB > /sys/bus/usb/drivers/usb/bind Make DEV the drive you want to reset, and run - it'll extract the USB port number and unbind/bind it (untested).
    – unfa
    Sep 11, 2019 at 10:56
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usbutils includes usbreset.

Run it without any arguments to see usage and a list of devices. It requires superuser access to actually reset devices.

Usage:
usbreset PPPP:VVVV - reset by product and vendor id
usbreset BBB/DDD   - reset by bus and device number
usbreset "Product" - reset by product name

This allows resetting individual devices which is an improvement over some answers that reset the entire bus. It might not resolve intermediary hub/bus issues, but it's a lot less disruptive to only reset the desired device.

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You can restart the hardware abstraction layer: sudo /etc/init.d/hal restart

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    i think HAL is replaced by something else in the newest version of ubuntu.. so its depend of distrib..
    – bAN
    Aug 17, 2010 at 20:29
  • 1
    I seriously doubt it would have worked anyway. HAL wasn't a low-level abstraction layer like the Windows component of the same name.
    – sourcejedi
    Dec 10, 2012 at 12:18

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