USB driver problem with external hub

USB driver problem with external hub

[cihan öztürk]

I am working on a device driver for providing connectivity to a Silabs
F340 board through USB. All the required software, including firmware
on the device side, USB device driver and user level libraries as well
as the application, are implemented. The system operates fine when
experimental communication is considered, in which dummy data is
simply sent and received betweeen the host and the device at Full
speed. The trouble comes when a USB external hub is used as a gateway
between the device and the host instead of directly connecting the USB
cable from device to the USB port of the PC. The kernel log states
that the transfer of urb failed due to -EPROTO(-71), which is defined
as protocol error. I found in some resources that this error can be a
result of (a) bitstuff error, or (b) no response packet received
within the prescribed bus turn-around time, or (c)hardware problems
such as bad devices (including firmware) or cables.
The hub is a Digitus product with 7 ports and works fine with other
USB devices such as the mouse on the same platform.
My kernel version is 2.6.18.
Has anyone got any idea on what can be the reason of this failure, and
how can I resolve the problem? I can surely provide any additional
information about the situation if any one is interested in helping
out.
Thanks... 
--------------
Cihan Ozturk


      

Re: USB driver problem with external hub

[Greg KH]

On Sat, Sep 20, 2008 at 04:35:03PM -0700, cihan öztürk wrote:
> I am working on a device driver for providing connectivity to a Silabs
> F340 board through USB. All the required software, including firmware
> on the device side, USB device driver and user level libraries as well
> as the application, are implemented. The system operates fine when
> experimental communication is considered, in which dummy data is
> simply sent and received betweeen the host and the device at Full
> speed. The trouble comes when a USB external hub is used as a gateway
> between the device and the host instead of directly connecting the USB
> cable from device to the USB port of the PC. The kernel log states
> that the transfer of urb failed due to -EPROTO(-71), which is defined
> as protocol error. I found in some resources that this error can be a
> result of (a) bitstuff error, or (b) no response packet received
> within the prescribed bus turn-around time, or (c)hardware problems
> such as bad devices (including firmware) or cables.
> The hub is a Digitus product with 7 ports and works fine with other
> USB devices such as the mouse on the same platform.
> My kernel version is 2.6.18.

Is this because you are using a USB 2.0 hub, connected via EHCI and your
device is a 1.1 speed device?  If so, this is a known issue with older
kernel versions, and has partially been fixed in newer kernel releases.

Please try 2.6.26 and let us know if that solves the issue.

Or just use a 1.1 hub, that should also work.

thanks,

greg k-h