Re: device model documentation 2/3

[Patrick Mochel <mochel@osdl.org>]

On Wed, 5 Jun 2002, Oliver Neukum wrote:

> 
> > Whether suspend is called with a given level is a policy of the
> > platform. Some levels may be omitted; drivers must not assume the
> > reception of any level. However, all levels must be called in the
> > order above; i.e. notification will always come before disabling;
> > disabling the device will come before suspending the device.
> >
> > All calls are made with interrupts enabled, except for the
> > SUSPEND_POWER_DOWN level.
> 
> This is a slight problem for USB. We need to switch on interupts
> to send a message to the device. Is this provided for ?

Well, it all depends on what you want to do with USB devices during a 
suspend transition. I missed some of the discussion in the last few days, 
and I know you guys talked about it a little (I'm on the hotplug list, but 
I don't always pay attention ;) It's also been talked about before, though 
I don't think anything has come out of it. 

IIRC, USB device state won't be saved across power transitions. It will 
look like a "disconnect", and "reconnect" on resume. (Forgive me if that's 
not the right USB terminology; I'm just guessing). In that case, when the 
controller gets the SUSPEND_DISABLE call, it can shutdown all the 
devices, and you're done. Right?

	-pat


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