Commit 79bcf7b0 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
Browse files

USB: EHCI: change return value of qh_completions() 



This patch (as1658) cleans up the usage of qh_completions() in
ehci-hcd.  Currently the function's return value indicates whether any
URBs were given back; the idea was that the caller can scan the QH
over again to handle any URBs that were dequeued by a completion
handler.  This is not necessary; when qh_completions() is ready to
give back dequeued URBs, it does its own rescanning.

Therefore the new return value will be a flag indicating whether the
caller needs to unlink the QH.  This is more convenient than forcing
the caller to check qh->needs_rescan, and it makes a lot more sense --
why should "needs_rescan" imply that an unlink is needed?  The callers
are also changed to remove the unneeded rescans.

Lastly, the check for whether qh->qtd_list is non-empty is removed
from the start of qh_completions().  Two of the callers have to make
this test anyway, so the same test can simply be added to the other
two callers.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c1fdb68e

drivers/usb/host/ehci-q.c

+8 −14
Original line number Diff line number Diff line
@@ -292,8 +292,8 @@ static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh); 


/*

 * Process and free completed qtds for a qh, returning URBs to drivers.

 * Chases up to qh->hw_current.  Returns number of completions called,

 * indicating how much "real" work we did.

 * Chases up to qh->hw_current.  Returns nonzero if the caller should

 * unlink qh.

 */

static unsigned

qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
@@ -302,13 +302,9 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh) 
	struct list_head	*entry, *tmp;

	int			last_status;

	int			stopped;

	unsigned		count = 0;

	u8			state;

	struct ehci_qh_hw	*hw = qh->hw;



	if (unlikely (list_empty (&qh->qtd_list)))

		return count;



	/* completions (or tasks on other cpus) must never clobber HALT

	 * till we've gone through and cleaned everything up, even when

	 * they add urbs to this qh's queue or mark them for unlinking.
@@ -345,7 +341,6 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh) 
		if (last) {

			if (likely (last->urb != urb)) {

				ehci_urb_done(ehci, last->urb, last_status);

				count++;

				last_status = -EINPROGRESS;

			}

			ehci_qtd_free (ehci, last);
@@ -519,7 +514,6 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh) 
	/* last urb's completion might still need calling */

	if (likely (last != NULL)) {

		ehci_urb_done(ehci, last->urb, last_status);

		count++;

		ehci_qtd_free (ehci, last);

	}
@@ -566,7 +560,7 @@ qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh) 
		/* otherwise, unlink already started */

	}



	return count;

	return qh->needs_rescan;

}



/*-------------------------------------------------------------------------*/
@@ -1254,6 +1248,7 @@ static void end_unlink_async(struct ehci_hcd *ehci) 
		qh->qh_state = QH_STATE_IDLE;

		qh->qh_next.qh = NULL;



		if (!list_empty(&qh->qtd_list))

			qh_completions(ehci, qh);

		if (!list_empty(&qh->qtd_list) &&

				ehci->rh_state == EHCI_RH_RUNNING)
@@ -1348,7 +1343,7 @@ static void scan_async (struct ehci_hcd *ehci) 
	while (ehci->qh_scan_next) {

		qh = ehci->qh_scan_next;

		ehci->qh_scan_next = qh->qh_next.qh;

 rescan:



		/* clean any finished work for this qh */

		if (!list_empty(&qh->qtd_list)) {

			int temp;
@@ -1361,14 +1356,13 @@ static void scan_async (struct ehci_hcd *ehci) 
			 * in single_unlink_async().

			 */

			temp = qh_completions(ehci, qh);

			if (qh->needs_rescan) {

			if (unlikely(temp)) {

				start_unlink_async(ehci, qh);

			} else if (list_empty(&qh->qtd_list)

					&& qh->qh_state == QH_STATE_LINKED) {

				qh->unlink_cycle = ehci->async_unlink_cycle;

				check_unlinks_later = true;

			} else if (temp != 0)

				goto rescan;

			}

		}

	}

drivers/usb/host/ehci-sched.c

+5 −7
Original line number Diff line number Diff line
@@ -649,6 +649,7 @@ static void end_unlink_intr(struct ehci_hcd *ehci, struct ehci_qh *qh) 
	qh->qh_state = QH_STATE_IDLE;

	hw->hw_next = EHCI_LIST_END(ehci);



	if (!list_empty(&qh->qtd_list))

		qh_completions(ehci, qh);



	/* reschedule QH iff another request is queued */
@@ -914,7 +915,7 @@ static void scan_intr(struct ehci_hcd *ehci) 


	list_for_each_entry_safe(qh, ehci->qh_scan_next, &ehci->intr_qh_list,

			intr_node) {

 rescan:



		/* clean any finished work for this qh */

		if (!list_empty(&qh->qtd_list)) {

			int temp;
@@ -927,12 +928,9 @@ static void scan_intr(struct ehci_hcd *ehci) 
			 * in qh_unlink_periodic().

			 */

			temp = qh_completions(ehci, qh);

			if (unlikely(qh->needs_rescan ||

					(list_empty(&qh->qtd_list) &&

			if (unlikely(temp || (list_empty(&qh->qtd_list) &&

					qh->qh_state == QH_STATE_LINKED)))

				start_unlink_intr(ehci, qh);

			else if (temp != 0)

				goto rescan;

		}

	}

}

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