Re: [RFD] Automatic suspend

Arjan van de Ven
2009-02-18T14:51:58Z

On Wed, 18 Feb 2009 09:53:48 +0100
Oliver Neukum <oliver@neukum.org> wrote:

> Am Wednesday 18 February 2009 00:26:53 schrieb Rafael J. Wysocki:
> > > Another possibility is to set up independent runtime PM for the
> > > transport and the device.  This means allowing the possibility
> > > that the transport is suspended while its child (the device) is
> > > not.  This is a little simpler (there's only one idle-timeout per
> > > device, since the link is treated as an independent device), but
> > > it violates the principle of never suspending a parent while
> > > there is an active child.
> >
> > Well, I think the first approach would be better.
>
> I am afraid it wouldn't be. How do you deal with shared transports?
>

realistically, something like this you need to design like this
Step 1) Assume the hardware is smart and can do this for you on the fly,
but it might need guidance.
(For many busses there are platforms that do this)
Step 2) For hardware that is not smart, emulate the smartness in the
driver, with help of the subsystem. These two together have
the right knowledge to make such decisions.

--
Arjan van de Ven Intel Open Source Technology Centre
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