Commit a448c9d8 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: EHCI: change deschedule logic for interrupt QHs 



This patch (as1281) changes the way ehci-hcd deschedules interrupt
QHs, copying the approach used for async QHs.  The caller is no longer
responsible for rescheduling the QH if its queue is non-empty; instead
the reschedule is done directly by intr_deschedule(), after calling
qh_completions().  This is exactly the same as how end_unlink_async()
works.

ehci_urb_dequeue() and intr_deschedule() now correctly handle the case
where they are called while another interrupt URB for the same QH is
being given back.  This was a surprisingly large blind spot.  And
scan_periodic() now respects the new needs_rescan flag.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 3a44494e

drivers/usb/host/ehci-hcd.c

+4 −22
Original line number Diff line number Diff line
@@ -934,8 +934,9 @@ static int ehci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status) 
			break;

		switch (qh->qh_state) {

		case QH_STATE_LINKED:

		case QH_STATE_COMPLETING:

			intr_deschedule (ehci, qh);

			/* FALL THROUGH */

			break;

		case QH_STATE_IDLE:

			qh_completions (ehci, qh);

			break;
@@ -944,23 +945,6 @@ static int ehci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status) 
					qh, qh->qh_state);

			goto done;

		}



		/* reschedule QH iff another request is queued */

		if (!list_empty (&qh->qtd_list)

				&& HC_IS_RUNNING (hcd->state)) {

			rc = qh_schedule(ehci, qh);



			/* An error here likely indicates handshake failure

			 * or no space left in the schedule.  Neither fault

			 * should happen often ...

			 *

			 * FIXME kill the now-dysfunctional queued urbs

			 */

			if (rc != 0)

				ehci_err(ehci,

					"can't reschedule qh %p, err %d",

					qh, rc);

		}

		break;



	case PIPE_ISOCHRONOUS:
@@ -1079,12 +1063,10 @@ ehci_endpoint_reset(struct usb_hcd *hcd, struct usb_host_endpoint *ep) 
			 * while the QH is active.  Unlink it now;

			 * re-linking will call qh_refresh().

			 */

			if (eptype == USB_ENDPOINT_XFER_BULK) {

			if (eptype == USB_ENDPOINT_XFER_BULK)

				unlink_async(ehci, qh);

			} else {

			else

				intr_deschedule(ehci, qh);

				(void) qh_schedule(ehci, qh);

			}

		}

	}

	spin_unlock_irqrestore(&ehci->lock, flags);

drivers/usb/host/ehci-q.c

+3 −9
Original line number Diff line number Diff line
@@ -299,7 +299,6 @@ __acquires(ehci->lock) 
static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);

static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);



static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh);

static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh);



/*
@@ -555,14 +554,9 @@ halt: 
			 * That should be rare for interrupt transfers,

			 * except maybe high bandwidth ...

			 */

			if ((cpu_to_hc32(ehci, QH_SMASK)

					& hw->hw_info2) != 0) {

				intr_deschedule (ehci, qh);

				(void) qh_schedule (ehci, qh);

			} else {



			/* Tell the caller to start an unlink */

			qh->needs_rescan = 1;

			}

			break;

		/* otherwise, unlink already started */

		}

drivers/usb/host/ehci-sched.c

+33 −3
Original line number Diff line number Diff line
@@ -617,6 +617,17 @@ static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh) 
{

	unsigned		wait;

	struct ehci_qh_hw	*hw = qh->hw;

	int			rc;



	/* If the QH isn't linked then there's nothing we can do

	 * unless we were called during a giveback, in which case

	 * qh_completions() has to deal with it.

	 */

	if (qh->qh_state != QH_STATE_LINKED) {

		if (qh->qh_state == QH_STATE_COMPLETING)

			qh->needs_rescan = 1;

		return;

	}



	qh_unlink_periodic (ehci, qh);
@@ -636,6 +647,24 @@ static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh) 
	qh->qh_state = QH_STATE_IDLE;

	hw->hw_next = EHCI_LIST_END(ehci);

	wmb ();



	qh_completions(ehci, qh);



	/* reschedule QH iff another request is queued */

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

			HC_IS_RUNNING(ehci_to_hcd(ehci)->state)) {

		rc = qh_schedule(ehci, qh);



		/* An error here likely indicates handshake failure

		 * or no space left in the schedule.  Neither fault

		 * should happen often ...

		 *

		 * FIXME kill the now-dysfunctional queued urbs

		 */

		if (rc != 0)

			ehci_err(ehci, "can't reschedule qh %p, err %d\n",

					qh, rc);

	}

}



/*-------------------------------------------------------------------------*/
@@ -2213,7 +2242,8 @@ restart: 
				type = Q_NEXT_TYPE(ehci, q.qh->hw->hw_next);

				q = q.qh->qh_next;

				modified = qh_completions (ehci, temp.qh);

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

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

						temp.qh->needs_rescan))

					intr_deschedule (ehci, temp.qh);

				qh_put (temp.qh);

				break;

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