Absolutely Tech

[Solved] Unable to enumerate USB device (Disabling ehci_hcd)

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:
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Recovering from corrupt upgrade from Jaunty to Karmic

I was excited for the Karmic Koala (v. 9.10) which came out yesterday and I happily started the download and kept the computer switched on overnight for the download to complete. When I woke up, surely the download was completed and I went on to install the downloaded packages. Which the installation was taking place, power went off and computer switched off abruptly. I was in shock and feared I wouldn’t be able to boot into Ubuntu again.

My fears came true when booting process stopped at “waiting for /dev/sda6”. I waited for quite a while but it would never proceed to next step. I pressed Esc and I was dropped into root terminal. I at once did

dpkg --configure -a

That didn’t help much. It gave me error “Read-only file system”. So, I made the file-system writable by doing

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