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usb: gadget: udc: core: Document the relation between usb_ep_queue() and completion callback

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Improve the kerneldoc for usb_ep_queue() to note explicitly that the
request's completion routine will be called if and only if the return
value is 0.  The corresponding fact about usb_submit_urb() for the
host-side API has long been documented, and this has always been the
intention for the gadget API.  But until now, documentation seems to
have been lacking.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Alan Stern 2018-03-27 10:27:06 -04:00 committed by Felipe Balbi
parent 6d08b06e67
commit 5d1332a8ea
1 changed files with 6 additions and 0 deletions
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6
drivers/usb/gadget/udc/core.c
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@ -244,6 +244,12 @@ EXPORT_SYMBOL_GPL(usb_ep_free_request);
* Returns zero, or a negative error code. Endpoints that are not enabled
* report errors; errors will also be
* reported when the usb peripheral is disconnected.
*
* If and only if @req is successfully queued (the return value is zero),
* @req->complete() will be called exactly once, when the Gadget core and
* UDC are finished with the request. When the completion function is called,
* control of the request is returned to the device driver which submitted it.
* The completion handler may then immediately free or reuse @req.
*/
int usb_ep_queue(struct usb_ep *ep,
struct usb_request *req, gfp_t gfp_flags)