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usb: ehci: remove wmb in qh_update

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qh_refresh is always called when the qh is idle and has not been
linked into hardware queue, so EHCI will not access overlay of
the qh at this time. Just before linking qh into hardware queue, there
has already one wmb to order writing qh descriptor and writing dma
address of the qh into hardware queue, so HC can always see
up-to-date qh descriptor once the qh is fetched with its dma address
by EHCI.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Ming Lei 2011-09-05 21:05:55 +08:00 committed by Greg Kroah-Hartman
parent 65e52f41fa
commit 0412560e18
1 changed files with 0 additions and 2 deletions
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2
drivers/usb/host/ehci-q.c
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@ -111,8 +111,6 @@ qh_update (struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd)
}
}
/* HC must see latest qtd and qh data before we clear ACTIVE+HALT */
wmb ();
hw->hw_token &= cpu_to_hc32(ehci, QTD_TOGGLE | QTD_STS_PING);
}