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Commit f579c2b4 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB Gadget: documentation update 



This patch (as1102) clarifies two points in the USB Gadget kerneldoc:

	Request completion callbacks are always made with interrupts
	disabled;

	Device controllers may not support STALLing the status stage
	of a control transfer after the data stage is over.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Acked-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent e0d795e4

include/linux/usb/gadget.h

+6 −2
Original line number Original line Diff line number Diff line
@@ -33,7 +33,8 @@ struct usb_ep; 
 * @short_not_ok: When reading data, makes short packets be

 * @short_not_ok: When reading data, makes short packets be

 *     treated as errors (queue stops advancing till cleanup).

 *     treated as errors (queue stops advancing till cleanup).

 * @complete: Function called when request completes, so this request and

 * @complete: Function called when request completes, so this request and

 *	its buffer may be re-used.

 *	its buffer may be re-used.  The function will always be called with

 *	interrupts disabled, and it must not sleep.

 *	Reads terminate with a short packet, or when the buffer fills,

 *	Reads terminate with a short packet, or when the buffer fills,

 *	whichever comes first.  When writes terminate, some data bytes

 *	whichever comes first.  When writes terminate, some data bytes

 *	will usually still be in flight (often in a hardware fifo).

 *	will usually still be in flight (often in a hardware fifo).
@@ -271,7 +272,10 @@ static inline void usb_ep_free_request(struct usb_ep *ep, 
 * (Note that some USB device controllers disallow protocol stall responses

 * (Note that some USB device controllers disallow protocol stall responses

 * in some cases.)  When control responses are deferred (the response is

 * in some cases.)  When control responses are deferred (the response is

 * written after the setup callback returns), then usb_ep_set_halt() may be

 * written after the setup callback returns), then usb_ep_set_halt() may be

 * used on ep0 to trigger protocol stalls.

 * used on ep0 to trigger protocol stalls.  Depending on the controller,

 * it may not be possible to trigger a status-stage protocol stall when the

 * data stage is over, that is, from within the response's completion

 * routine.

 *

 *

 * For periodic endpoints, like interrupt or isochronous ones, the usb host

 * For periodic endpoints, like interrupt or isochronous ones, the usb host

 * arranges to poll once per interval, and the gadget driver usually will

 * arranges to poll once per interval, and the gadget driver usually will