Re: [PATCH] implement pm_ops.valid for everybody

Rafael J. Wysocki
2007-03-21T23:32:24Z

On Wednesday, 21 March 2007 23:57, Pavel Machek wrote:
> Hi!
>
> > > Which is very much an indication of how weak ACPI is. It
> > > doesn't contemplate typical SOC behavior, which have a wide
> > > variety of system sleep states that leave the CPU on ... and
> > > which may not even *have* (or need!) a "cpu off" state.
> > >
> > > My own definition would be more like: the minimal RAM-based
> > > power-saving system state is "standby". If the system
> > > implements a deeper RAM-based system sleep state, that's "STR".
> >
> > Hmmm, this leaves the decision how to call each state COMPLETELY to the
> > implementor, doesn't it?
>
> Is that a problem? If someone is clever enough to implement suspend, I
> think we can trust them to name their states right.
>
> (And trust me, we can flame them if not).
>
> (Anyway, my definition would be "mem" == RAM is powered, everything
> else is down, except for devices needed for wakeup; "standby" ==
> something is powered that can be powered down, we'll fix that in next version).

I think we can define "standby" a bit more precisely. Something like:
- processes are frozen,
- devices are suspended,
- nonboot CPUs are down (and in low powered states, if possible),
- "system" devices may or may not be suspended, depending on the platform,
- the boot CPU may or may not be in a low power state, depending on the platform,
- RAM is powered
- wake up need not be BIOS-driven (main difference from "mem")

Greetings,
Rafael