usb_ep_alloc_request — allocate a request object to use with this endpoint
| struct usb_request * usb_ep_alloc_request ( | struct usb_ep * ep, | 
| gfp_t gfp_flags ); | 
   Request objects must be allocated with this call, since they normally
   need controller-specific setup and may even need endpoint-specific
   resources such as allocation of DMA descriptors.
   Requests may be submitted with usb_ep_queue, and receive a single
   completion callback.  Free requests with usb_ep_free_request, when
   they are no longer needed.
   
Returns the request, or null if one could not be allocated.