On Monday 16 March 2009, Alan Stern wrote:
> This patch (as1225) fixes a bug in ehci-hcd. The condition for
> whether unlinked QHs can become IDLE should not be that the controller
> is halted, but rather that the controller isn't running. In other
> words when the root hub is suspended, the hardware doesn't own any
> QHs.
>
> This fixes a problem that can show up during hibernation: If a QH is
> only partially unlinked when the root hub is frozen, then when the
> root hub is thawed the QH won't be in the IDLE state. As a result it
> can't be used properly for new URB submissions.
>
> Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Reported-and-tested-by: Brandon Philips <brandon@xxxxxxxx>
> CC: David Brownell <david-b@xxxxxxxxxxx>
Acked-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
.... for 2.6.29-final too, yes?
>
> ---
>
> Index: usb-2.6/drivers/usb/host/ehci-q.c
> ===================================================================
> --- usb-2.6.orig/drivers/usb/host/ehci-q.c
> +++ usb-2.6/drivers/usb/host/ehci-q.c
> @@ -1127,7 +1127,8 @@ static void start_unlink_async (struct e
> prev->qh_next = qh->qh_next;
> wmb ();
>
> - if (unlikely (ehci_to_hcd(ehci)->state == HC_STATE_HALT)) {
> + /* If the controller isn't running, we don't have to wait for it */
> + if (unlikely(!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))) {
> /* if (unlikely (qh->reclaim != 0))
> * this will recurse, probably not much
> */
>
>
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