Reset USB only working on some ports

teslaa · 05-14-2017, 05:25 AM

(Running RHEL) So I have a USB device plugged into a USB port and I'm attempting to reset it since sometimes on boot it does not start properly. The issue is that I can only reset it on some ports.

If I plug it in a port and it shows up as having a dot number for example 1-9.3 (confirmed by using dmesg) then I can reset it and have it start working by unbinding and binding the parent device number but it does not work if I specify that specific device. For example

Doing this resets the device and it starts working fine...

Code:

echo "1-9" > /sys/bus/usb/drivers/usb/unbind
echo "1-9" > /sys/bus/usb/drivers/usb/bind

However if I try the lines below instead it does not start working...

Code:

echo "1-9.3" > /sys/bus/usb/drivers/usb/unbind
echo "1-9.3" > /sys/bus/usb/drivers/usb/bind

Any ideas why?

The top solution is not an adequate solution as if I plug my device in a different port and it shows up as device 2-1 and doesn't have a dot number then doing the below does not work.

Code:

echo "2-1" > /sys/bus/usb/drivers/usb/unbind
echo "2-1" > /sys/bus/usb/drivers/usb/bind

ferrari · 05-16-2017, 08:10 PM

I don't know the answer to your question, but the behaviour might depend on the hub (XHCI, EHCI controller) concerned perhaps.

An alternative method that I've seen used might be to do this instead....

Code:

sudo sh -c "echo 0 > /sys/bus/usb/devices/2-1/authorized"
sudo sh -c "echo 1 > /sys/bus/usb/devices/2-1/authorized"

You can run between the above commands and at the end to observe the effect

Code:

lsusb -t