Re: [PATCH] usb ehci_iaa_watchdog fix
From: Alan Stern
Date: Wed Apr 02 2008 - 17:09:19 EST
On Wed, 2 Apr 2008, David Brownell wrote:
> > It fixes the cause rather than the symptom.
>
> I'm not sure I'd agree with that.
Really? The logic seemed clear enough to me.
1. Evidently the ehci_iaa_watchdog routine was getting called at a
time when the host controller wasn't running -- which had to
have been after it was suspended.
2. But ehci_bus_suspend() calls end_unlink_async(), which turns
off the IAA watchdog timer.
3. Hence the timer must have been restarted later on while
ehci_bus_suspend() was still running. The call to ehci_work()
appeared to be the only place that could have happened.
4. Thus moving the end_unlink_async() call to after ehci_work()
(or just to be doubly safe, after ehci_halt() and the change
to HC_STATE_SUSPENDED) should take care of all pending QH
unlinks and leave none of them unfinished.
Strictly speaking, it would be best to move the del_timer_sync() calls
to after ehci_lock is released. But it doesn't really matter if the
timer routines get invoked after the controller is suspended.
Alan Stern
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