Ubuntu. USB keeps disconnecting or not recognizing
 

All of a sudden, USB seems to be haywire. I was on Jaunty but upgraded to Karmic, but that did not fix anything.

USB devices will either not be recognized when I plug them in (a usb game pad or my blackberry), or will be recognized, then disconnect

When it does show up, after a few minutes, dmesg will show this:

[24931.888638] usb 2-9: USB disconnect, address 12
[24945.152039] hub 2-0:1.0: unable to enumerate USB device on port 9

It'll keep disconnecting, then slightly later recognize the device again, with a new address.

I've seen something similar to this and it turned out to be faulty hardware. Do you plug your devices into a hub or directly into the port? If so remove the hub, or a different cable.
You may also be a power problem.

It could possibly be software related though.

:)

It plugs directly into the port. I tested the same hardware on my wife's laptop running osX, and it works fine there. So Im thinking the cable is fine

It could also be the USB chipset in your mainboard.

Did a few more tests and my blackberry does connect fine every time.

I'll see if I can pick up another usb gamepad just to verify though it works on another computer okay

Similar issue on quantal
 

Did you ever find the reason for this issue or was it resolved? I have a similar issue in latest ubuntu quantal (12.10). I am connecting an MTP android device. The very first time it worked for some time, then it stopped. Later connecting/disconnecting the device doesn't show anything on dmesg. On reboot with the device connected physically, dmesg shows the device connection and disconnecton logs back to back.

[ 2.505545] usb 2-1.4: new high-speed USB device number 4 using ehci_hcd
[ 2.599906] usb 2-1.4: New USB device found, idVendor=04e8, idProduct=6860
[ 2.599921] usb 2-1.4: New USB device strings: Mfr=2, Product=3, SerialNumber=4
[ 2.599932] usb 2-1.4: Product: SAMSUNG_Android
[ 2.599939] usb 2-1.4: Manufacturer: SAMSUNG
[ 2.599946] usb 2-1.4: SerialNumber: 4d...5d
[ 2.652289] usb 2-1.4: USB disconnect, device number 4

The same works with windows dual boot on same machine. So don't think it is a hardware issue in anyway.