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: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: David Brownell <david-b@xxxxxxxxxxx>
---
Index: usb-2.6/drivers/usb/host/ehci-hcd.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci-hcd.c
+++ usb-2.6/drivers/usb/host/ehci-hcd.c
@@ -934,8 +934,9 @@ static int ehci_urb_dequeue(struct usb_h
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_h
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,
* 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);
Index: usb-2.6/drivers/usb/host/ehci-q.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci-q.c
+++ usb-2.6/drivers/usb/host/ehci-q.c
@@ -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;
- }
+
+ /* Tell the caller to start an unlink */
+ qh->needs_rescan = 1;
break;
/* otherwise, unlink already started */
}
Index: usb-2.6/drivers/usb/host/ehci-sched.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/ehci-sched.c
+++ usb-2.6/drivers/usb/host/ehci-sched.c
@@ -615,8 +615,19 @@ static int qh_unlink_periodic(struct ehc
static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
{
- unsigned wait;
- struct ehci_qh_hw *hw = qh->hw;
+ 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
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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