Some hardware just don’t work with ehci_hcd on Karmic Koala. My memory stick from transcend refused to work no matter what I did. After plugging the device nothing happened, doing dmesg showed me the following error:
Apr 18 10:59:04 dpac-laptop kernel: [73668.388060] usb 1-2: new high speed USB device using ehci_hcd and address 5
Apr 18 10:59:04 dpac-laptop kernel: [73668.473034] hub 1-0:1.0: unable to enumerate USB device on port 2
After searching a lot, I came to a conclusion that my device doesn’t work with USB 2.0. So I disabled the ehci_hcd to make it work.
Since Karmic doesn’t use ehci_hcd as a module, modprobe -r ehci_hcd no longer works. The module is compiled into kernel. To disable it execute the following commands in terminal:
cd /sys/bus/pci/drivers/ehci_hcd ls
You will see a file with 0000:00:xx.x format. Execute the following command:
sudo sh -c 'echo -n "0000:00:xx.x" > unbind'
Replace the xx.x with the numbers displayed on your file. It should disable the ehci_hcd.
I plugged in my memory stick, and it worked.
Please note that you’ll have to do all this each time you restart.
You can now use the following script to disable ehci_hcd. It is far more simpler since it just needs you copy pasting the commands instead of a manual action. Here it goes:
cd /sys/bus/pci/drivers/ehci_hcd/ sudo sh -c 'find ./ -name "0000:00:*" -print| sed "s/\.\///">unbind'