Re: [patch] pm: fix runtime powermanagement's /sys interface

Takashi Iwai
2006-01-13T20:00:46Z

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At Fri, 6 Jan 2006 04:24:22 +0000,
Pavel Machek wrote:
>
>
> > > > 1.) most sound cards have more than two states. (once again latency over
> > > > power savings trade offs)
> > >
> > > What is the latency in typical "most sound card" case?
> >
> > ACPI requires within 100ms for D1 and D2. D3 can be longer.
>
> Spec is useless here. 1usec is <100msec. Do you know any
> soundcard that takes >10msec from D3?

In the case of D3, the driver needs to initialize fully, and a latency
longer than 10ms may easily happen espeically with HZ=100.

Most of codec chips have powersave modes (disable converters and
amps), so having a "powersave" state makes sense, not only "on" and
"suspend".

Takashi

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