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: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 9 deletions

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 57a84795c43f..00ad9ce392ed 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/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 */
                 }