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, 4 insertions, 22 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index d7e85b6231b3..4f89d7ffd53a 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -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);