diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2008-06-02 16:26:48 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-07-21 15:16:27 -0700 |
| commit | f579c2b46f74038e8f5a762c7f10c2385b33e3dc (patch) | |
| tree | c59005c442589f61bb23ddce25e52d2f53b2990b /include | |
| parent | e0d795e4f36c2d8949c1355b497fc5425dbb9437 (diff) | |
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: Alan Stern <stern@rowland.harvard.edu>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/usb/gadget.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h index 0ebedaec075d..0460a746480c 100644 --- a/include/linux/usb/gadget.h +++ b/include/linux/usb/gadget.h @@ -33,7 +33,8 @@ struct usb_ep; * @short_not_ok: When reading data, makes short packets be * treated as errors (queue stops advancing till cleanup). * @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, * whichever comes first. When writes terminate, some data bytes * 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 * in some cases.) When control responses are deferred (the response is * 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 * arranges to poll once per interval, and the gadget driver usually will |