unable to enumerate USB device

Question

I have remote Pi, with several 4 USB devices. One device is attached directly in the board while other three devices are connected via USB hub (active hub, powered with supply capable of providing more than 3 A).

However it happens sometimes the following error:

[48.954052] usb 3-1.1: device descriptor read/64, error -110
[64.154185] usb 3-1.1: device descriptor read/64, error -110
[64.354992] usb 3-1.1: new full-speed USB device number 5 using sw-ehci
[74.784189] usb 3-1.1: device not accepting address 5, error -110
[74.875124] usb 3-1.1: new full-speed USB device number 6 using sw-ehci
[85.304183] usb 3-1.1: device not accepting address 6, error -110
[85.322332] hub 3-1:1.0: unable to enumerate USB device on port 1

I was not able to find out what means error -110 and how to restart USB device only by using driver calls.

Answer 1

The information I'm finding relating to 'error 110' suggests that you're exceeding the power limits of the USB port. I'd recommend that you:

• Use a meter to properly confirm the power output of your supply/supplies
• Experiment with reducing the total number of USB devices
• Experiment with removing the device directly attached to the Pi's USB port

Hopefully improving your power supply or reducing the draw from the USB port(s) will help.

To reset the USB bus, try the solution proposed in gurcanozturk's answer here.

Answer 2

I have the same problem. I have a 2 Amp USB charger and still, I couldn't get it to read for more than one device. I tried connecting another USB hub through the working USB port of the first USB hub, and voila! .. it works!