Re: [linux-pm] wacom + runtime PM = AA deadlock

From: Alan Stern
Date: Tue Sep 14 2010 - 10:01:22 EST


On Tue, 14 Sep 2010, Oliver Neukum wrote:

> Am Montag, 13. September 2010, 22:02:16 schrieb Alan Stern:
> > > > Is there any point in resuming the device during close() just in order
> > > > to kill the interrupt URB? It seems counterproductive -- if the device
> > > > had been suspended then there wouldn't be any interrupt URB to kill in
> > > > the first place.
> > >
> > > Suppose the device does not support remote wakeup. It would never
> > > be autosuspended while it is open, but simply resetting the flag
> > > would never reach the PM layer.
> >
> > Whoops, that's right. I didn't see the assignment to
> > needs_remote_wakeup.
>
> Should I have used usb_autopm_get_interface_no_resume()?

That actually would work. It's a good idea. The only drawback (not a
big one) is that if the device _was_ suspended with remote wakeup
enabled, doing this wouldn't turn off remote wakeup. I think that
doesn't matter.

Alan Stern

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