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USB: EHCI: changes related to qh_refresh()

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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>
This commit is contained in:
Alan Stern
2013-03-22 13:30:43 -04:00
committed by Greg Kroah-Hartman
parent c79041a440
commit c1fdb68e3d
2 changed files with 26 additions and 35 deletions
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9
drivers/usb/host/ehci-sched.c
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@@ -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++;