suse man page for usb_ifnum_to_if

USB_IFNUM_TO_IF(9)						   USB Core APIs						USB_IFNUM_TO_IF(9)

NAME
       usb_ifnum_to_if - get the interface object with a given interface number

SYNOPSIS
       struct usb_interface * usb_ifnum_to_if(const struct usb_device * dev, unsigned ifnum);

ARGUMENTS
       dev
	   the device whose current configuration is considered

       ifnum
	   the desired interface

DESCRIPTION
       This walks the device descriptor for the currently active configuration and returns a pointer to the interface with that particular
       interface number, or null.

       Note that configuration descriptors are not required to assign interface numbers sequentially, so that it would be incorrect to assume that
       the first interface in that descriptor corresponds to interface zero. This routine helps device drivers avoid such mistakes. However, you
       should make sure that you do the right thing with any alternate settings available for this interfaces.

       Don't call this function unless you are bound to one of the interfaces on this device or you have locked the device!

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010							USB_IFNUM_TO_IF(9)