USB: EHCI: changes related to qh_refresh()

This patch (as1638) makes several changes to the ehci-hcd driver, all
related to the qh_refresh() function.  This function must be called
whenever an idle QH gets linked back into either the async or the
periodic schedule.

	Change a BUG_ON() in the qh_update routine to a WARN_ON().
	Since this code runs in atomic context, a BUG_ON() would
	immediately freeze the whole system.

	Remove two unneeded calls to qh_refresh(), one when a QH is
	initialized and one when a QH becomes idle.  Adjust the
	adjacent comments accordingly.

	Move the qh_refresh() and qh_link_periodic() calls for new
	interrupt URBs to after the new TDs have been added.

	As a result of the previous two changes, qh_refresh() is never
	called when the qtd_list is empty.  The corresponding check in
	qh_refresh() can be removed, along with an indentation level.

These changes should not cause any alteration of behavior.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index b476daf49f6f..66259dc7822e 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -792,7 +792,6 @@ static int qh_schedule(struct ehci_hcd *ehci, struct ehci_qh *qh)
 	unsigned	frame;		/* 0..(qh->period - 1), or NO_FRAME */
 	struct ehci_qh_hw	*hw = qh->hw;
 
-	qh_refresh(ehci, qh);
 	hw->hw_next = EHCI_LIST_END(ehci);
 	frame = qh->start;
 
@@ -844,8 +843,6 @@ static int qh_schedule(struct ehci_hcd *ehci, struct ehci_qh *qh)
 	} else
 		ehci_dbg (ehci, "reused qh %p schedule\n", qh);
 
-	/* stuff into the periodic schedule */
-	qh_link_periodic(ehci, qh);
 done:
 	return status;
 }
@@ -891,6 +888,12 @@ static int intr_submit (
 	qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
 	BUG_ON (qh == NULL);
 
+	/* stuff into the periodic schedule */
+	if (qh->qh_state == QH_STATE_IDLE) {
+		qh_refresh(ehci, qh);
+		qh_link_periodic(ehci, qh);
+	}
+
 	/* ... update usbfs periodic stats */
 	ehci_to_hcd(ehci)->self.bandwidth_int_reqs++;