Re: [RFC] Linux Power Management

Pavel Machek
2005-05-09T19:30:39Z

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Hi!

> > If they use GPIO lines on chip that eats so much power that it must be
> > power-managed... yes, I'd call that broken hardware.
>
> By virtue of being in the driver model, it _is_ managed no
> matter how much power it uses (or doesn't use). The issue
> isn't how much power it uses. It's the expectation that all
> power signals only flow parallel to data and control busses,
> as they would on daughtercard based designs.
>
> I'd tend to agree with hardware guys on this one: this is
> such a simple case that only broken _software_ should have
> trouble handling it.
>
>
> > Of course, current pm core *is* inadequate for even simple uses...
>
> Right, and GPIO based power switching is a "simple use".
> Luckily the init sequence tweaks I described make Linux
> work with it, until selective suspend kicks in.

Well, GPIO power switching should be very easy to handle ... as long
as path between CPU and GPIO-based-power-switches takes little
power. When we don't have to power-manage the path between CPU and
GPIO-based-power-switches, we are fine...
Pavel
--
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