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USB: gadget: Document that certain ep operations can be called in interrupt context

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This documentation patch specifies that certain USB gadget endpoint
operations may be called in interrupt context:

	usb_ep_queue, usb_ep_dequeue, usb_ep_set_halt,
	usb_ep_clear_halt, usb_ep_set_wedge, usb_ep_fifo_status,
	and usb_ep_fifo_flush;

while others must be called in process context:

	usb_ep_enable and usb_ep_disable.

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 2018-06-29 13:52:20 -04:00 committed by Felipe Balbi
parent ad22a6663c
commit bf594c1070
1 changed files with 18 additions and 0 deletions
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18
drivers/usb/gadget/udc/core.c
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@ -87,6 +87,8 @@ EXPORT_SYMBOL_GPL(usb_ep_set_maxpacket_limit);
* configurable, with more generic names like "ep-a". (remember that for
* USB, "in" means "towards the USB master".)
*
* This routine must be called in process context.
*
* returns zero, or a negative error code.
*/
int usb_ep_enable(struct usb_ep *ep)
@ -119,6 +121,8 @@ EXPORT_SYMBOL_GPL(usb_ep_enable);
* gadget drivers must call usb_ep_enable() again before queueing
* requests to the endpoint.
*
* This routine must be called in process context.
*
* returns zero, or a negative error code.
*/
int usb_ep_disable(struct usb_ep *ep)
@ -241,6 +245,8 @@ EXPORT_SYMBOL_GPL(usb_ep_free_request);
* Note that @req's ->complete() callback must never be called from
* within usb_ep_queue() as that can create deadlock situations.
*
* This routine may be called in interrupt context.
*
* 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.
@ -284,6 +290,8 @@ EXPORT_SYMBOL_GPL(usb_ep_queue);
* at the head of the queue) except as part of disconnecting from usb. Such
* restrictions prevent drivers from supporting configuration changes,
* even to configuration zero (a "chapter 9" requirement).
*
* This routine may be called in interrupt context.
*/
int usb_ep_dequeue(struct usb_ep *ep, struct usb_request *req)
{
@ -311,6 +319,8 @@ EXPORT_SYMBOL_GPL(usb_ep_dequeue);
* 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.
*
* This routine may be called in interrupt context.
*
* 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
@ -336,6 +346,8 @@ EXPORT_SYMBOL_GPL(usb_ep_set_halt);
* for endpoints that aren't reconfigured, after clearing any other state
* in the endpoint's i/o queue.
*
* This routine may be called in interrupt context.
*
* 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),
@ -360,6 +372,8 @@ EXPORT_SYMBOL_GPL(usb_ep_clear_halt);
* requests. If the gadget driver clears the halt status, it will
* automatically unwedge the endpoint.
*
* This routine may be called in interrupt context.
*
* Returns zero on success, else negative errno.
*/
int usb_ep_set_wedge(struct usb_ep *ep)
@ -388,6 +402,8 @@ EXPORT_SYMBOL_GPL(usb_ep_set_wedge);
* written OUT to it by the host. Drivers that need precise handling for
* fault reporting or recovery may need to use this call.
*
* This routine may be called in interrupt context.
*
* This returns the number of such bytes in the fifo, or a negative
* errno if the endpoint doesn't use a FIFO or doesn't support such
* precise handling.
@ -415,6 +431,8 @@ EXPORT_SYMBOL_GPL(usb_ep_fifo_status);
* an endpoint fifo after abnormal transaction terminations. The call
* must never be used except when endpoint is not being used for any
* protocol translation.
*
* This routine may be called in interrupt context.
*/
void usb_ep_fifo_flush(struct usb_ep *ep)
{