Scanner/webcam not working when connected to USB hub

Scanner/webcam not working when connected to USB hub

[Hervé Fache]

Hello guys,

I have the following problem: if connected directly to my computer's
USB ports, my webcam works correctly, but when connected through my
'AirVast' hub (124a:168b), it fails. The device is reported by lsusb
(IDs correct), but it does not work. The worst is: I have tried using
some proprietary OS, and it all worked there.

There are two possibilities (did I miss one?) I guess: either libusb
is playing, or the kernel USB stack is.

Now, rather than giving work to others, I don't mind trying to find
the problem myself, but I would appreciate a pointer to how to debug
such a problem... Tools? Compilation options?

Cheers,
Hervé.

Kernel: 2.6.12 from Kubuntu

Hub Descriptor:
  bLength               9
  bDescriptorType      41
  nNbrPorts             3
  wHubCharacteristic 0x0002
    No power switching (usb 1.0)
    Ganged overcurrent protection
  bPwrOn2PwrGood        1 * 2 milli seconds
  bHubContrCurrent      0 milli Ampere
  DeviceRemovable    0xf0
  PortPwrCtrlMask    0x37
 Hub Port Status:
   Port 1: 0000.0103 power enable connect
   Port 2: 0000.0100 power
   Port 3: 0000.0103 power enable connect

Re: Scanner/webcam not working when connected to USB hub

[Greg KH]

On Mon, Dec 05, 2005 at 11:19:05AM -0200, Herv? Fache wrote:
> Hello guys,
> 
> I have the following problem: if connected directly to my computer's
> USB ports, my webcam works correctly, but when connected through my
> 'AirVast' hub (124a:168b), it fails. The device is reported by lsusb
> (IDs correct), but it does not work. The worst is: I have tried using
> some proprietary OS, and it all worked there.

Is it a USB 1.1 device connected to a USB 2.0 hub?  If so, Linux
currently has some issues with running properly for this setup.  See the
linux-usb-devel mailing list archives for some patches that some people
have found to resolve this.

thanks,

greg k-h

Re : Scanner/webcam not working when connected to USB hub

[Hervé Fache]

Sorry I missed this important point in my message. You're right. I
shall check the mailing lists you supplied and report success there if
any.

Cheers,
Hervé.