ep
Use this when responding to the standard usb lqset interfacerq request, for endpoints that aren't reconfigured, after clearing any other state in the endpoint's i/o queue.
Returns zero, or a negative error code. On success, this call clears the underlying hardware state reflecting endpoint halt and data toggle. Note that some hardware can't support this request (like pxa2xx_udc), and accordingly can't correctly implement interface altsettings.
David Brownell <dbrownell@users.sourceforge.net>