Either my Dell Optiplex 990 computer or my Linux install has an issue: occasionally, when I re-plug a USB device into the system, it’ll cause a fault in the USB module in the kernel and USB goes dark. I’m unsure as to whether this is a hardware or software issue, but I’d simply like to restart my USB subsystem and continue working. When searching the web for ‘restart USB in Linux’ and ‘reload USB kernel module’, you get a plethora of results and none of which will work (seemingly due to how the Ubuntu standard kernel is compiled), at least for me within Ubuntu 12.04, Precise Pangolin. Until now, I’ve had no success and had to hard reset. No longer.
You’ll need root/sudo access to the machine to be able to run commands. In my case, without USB available, then I’ve either got to sprint for a PS/2 keyboard and mouse or login via SSH. You can do what I’ve done and prepared things into a suitable script I can run with just a Gnome launcher. Thanks to this fantastic post for the help. Either place the following into a script or run the commands directly:
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
The hardware identifiers being passed around here can be revealed using a command like lspci | grep USB. In my case, the identifiers in the original post were exactly what I have in my system.
I’m yet to see if my USB will correctly come back online after freezing up as it hasn’t happened yet, but I’ll try this when it does and report back. That said, the commands above definitely reload all USB devices attached to the system; that much I’ve tried.
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