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NAME

       usb_ep_dequeue  -  dequeues  (cancels,  unlinks) an I/O request from an
       endpoint

SYNOPSIS

       int usb_ep_dequeue  (struct usb_ep * ep, struct usb_request * req);

ARGUMENTS

       ep     the endpoint associated with the request

       req    the request being canceled

DESCRIPTION

       if the request is still active on the endpoint, it is dequeued and  its
       completion routine is called (with status -ECONNRESET); else a negative
       error code is returned.

       note that some hardware can’t clear out  write  fifos  (to  unlink  the
       request  at the head of the queue) except as part of disconnecting from
       usb. such restrictions prevent drivers  from  supporting  configuration
       changes, even to configuration zero (a ‘‘chapter 9’’ requirement).

AUTHOR

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