Re: USB ports not working after device disconnect
On Wed, 08 Aug 2012 12:25:46 +0100, Laurence Hurst wrote:
> Occasionally, when I disconnect a device (usually a mass storage device)
> from my laptop (Lenovo Thinkpad x201), the USB ports stop recognising
> devices when I plug them in until I reboot. The ports are still powered
> and will charge e.g. a phone if I plug one in but nothing at all is
> registered by dmesg or logged in /var/log/messages.
Weird. Check if there's a BIOS update, just in case.
> Last time this happened lsusb showed a 'linux root hub' and an 'Intel
> rate matching hub' and nothing else. I've rebooted the machine and then
> had two of each of these (there was only 1 before) along with the
> inbuilt fingerprint reader and a device just described as "Lenovo",
> which suggests to me Debian is somehow losing one of the root hubs.
Kernel does not usually lose USB hubs, it only shows what is there and
presents nothing when either a) a hardware problem arises or b) a bug is
hitting you :-)
So, to discard a kernel problem you can try by loading a different kernel
release (better an updated version). This can be easily done from a
LiveCD (nothing to install) or getting a new kernel version (from the
backports or compiling yourself from sources).
> Before I rebooted it last time, I tried removing and reprobing the usb
> modules (i.e. usbcore and anything which depend on it) but this made no
> difference.
Mmm... I was going to suggest precisely that (i.e., modprobe -r usbcore
modporbe usbcore).
What Debian flavour are you running?
> Anyone any idea why this might be happening, or what I can do to try and
> fix it?
Problems with USB ports usually come from power issues (a damaged USB
controller which cannot provide 5V to the ports can cause devices
attached to it that require more power are not properly detected or
experience random disconnects). You can run the usual tests: try with
different devices other than mass storage, replace the USB cable (if
any), attach the device to a different port, etc...
Greetings,
--
Camaleón
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