Querying USB device's bInterfaceNumber

[Greg KH]

On Tue, Nov 03, 2009 at 10:03:18AM -0800, Ping wrote:
> I need a quick answer since searching through the X server code takes too
> long.
> 
> Is there a way for me to get the bInterfaceNumber from a device HID
> Descriptor inside an xorg Input device driver?  I feel there should be an
> existing mechanism to fulfil this, maybe through an ioctl call?  Can someone
> show me what parameter(s) I need to use if the ioctl is supported?
> 
> Please also reply to me if you know there is no existing way to get the
> bInterfaceNumber inside an xorg device driver so I will add my own
> workaround in the kernel driver.

The kernel already exports this information to userspace, so you do not
need to add it to your specific kernel driver.  So it should be possible
to do this for all USB devices.

thanks,

greg k-h