Re: [PATCH] usb ehci_iaa_watchdog fix

Alan Stern
2008-04-02T21:09:18Z

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