centos man page for usb_ep_fifo_status

USB_EP_FIFO_STATUS(9)					      Kernel Mode Gadget API					     USB_EP_FIFO_STATUS(9)

NAME
       usb_ep_fifo_status - returns number of bytes in fifo, or error

SYNOPSIS
       int usb_ep_fifo_status(struct usb_ep * ep);

ARGUMENTS
       ep
	   the endpoint whose fifo status is being checked.

DESCRIPTION
       FIFO endpoints may have "unclaimed data" in them in certain cases, such as after aborted transfers. Hosts may not have collected all the IN
       data written by the gadget driver (and reported by a request completion). The gadget driver may not have collected all the data written OUT
       to it by the host. Drivers that need precise handling for fault reporting or recovery may need to use this call.

       This returns the number of such bytes in the fifo, or a negative errno if the endpoint doesn't use a FIFO or doesn't support such precise
       handling.

AUTHOR
       David Brownell <dbrownell@users.sourceforge.net>
	   Author.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						     USB_EP_FIFO_STATUS(9)