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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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12
drivers/usb/host/ehci-q.c
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@@ -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 */
}