usb_ep_set_halt(9) sets the endpoint halt feature.


int usb_ep_set_halt(struct usb_ep * ep);



the non-isochronous endpoint being stalled


Use this to stall an endpoint, perhaps as an error report. Except for control endpoints, the endpoint stays halted (will not stream any data) until the host clears this feature; drivers may need to empty the endpoint's request queue first, to make sure no inappropriate transfers happen.

Note that while an endpoint CLEAR_FEATURE will be invisible to the gadget driver, a SET_INTERFACE will not be. To reset endpoints for the current altsetting, see usb_ep_clear_halt. When switching altsettings, it's simplest to use usb_ep_enable or usb_ep_disable for the endpoints.

Returns zero, or a negative error code. On success, this call sets underlying hardware state that blocks data transfers. Attempts to halt IN endpoints will fail (returning -EAGAIN) if any transfer requests are still queued, or if the controller hardware (usually a FIFO) still holds bytes that the host hasn't collected.


David Brownell <[email protected]>