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USB: EHCI: change deschedule logic for interrupt QHs

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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@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2009-08-19 12:22:44 -04:00 committed by Greg Kroah-Hartman
parent 3a44494e23
commit a448c9d8c5
3 changed files with 40 additions and 34 deletions
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26
drivers/usb/host/ehci-hcd.c
View file

@ -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);

12
drivers/usb/host/ehci-q.c
View file

@ -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 */
}

36
drivers/usb/host/ehci-sched.c
View file

@ -615,8 +615,19 @@ static int qh_unlink_periodic(struct ehci_hcd *ehci, struct ehci_qh *qh)
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_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;