struct_usb_interface_cache(9) suse man page | unix.com

STRUCT 
USB_INTERFACE(9) 				  Host-Side Data Types and Macro				   STRUCT USB_INTERFACE(9)

NAME
       struct_usb_interface_cache - long-term representation of a device interface

SYNOPSIS
       struct usb_interface_cache {
	 unsigned num_altsetting;
	 struct kref ref;
	 struct usb_host_interface altsetting[0];
       };

MEMBERS
       num_altsetting
	   number of altsettings defined.

       ref
	   reference counter.

       altsetting[0]
	   variable-length array of interface structures, one for each alternate setting that may be selected. Each one includes a set of endpoint
	   configurations. They will be in no particular order.

DESCRIPTION
       These structures persist for the lifetime of a usb_device, unlike struct usb_interface (which persists only as long as its configuration is
       installed). The altsetting arrays can be accessed through these structures at any time, permitting comparison of configurations and
       providing support for the /proc/bus/usb/devices pseudo-file.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010						   STRUCT USB_INTERFACE(9)