Re: [PATCH] implement pm_ops.valid for everybody

Rafael J. Wysocki
2007-03-22T21:33:04Z

On Thursday, 22 March 2007 14:44, Scott E. Preece wrote:
>
> | From: "Rafael J. Wysocki" <rjw@sisk.pl>
> |
> | 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")
> ---
>
> I would be tempted to say that that last bullet is the distinguishing
> characteristic - that you come back from standby by just continuing
> where you left off, but you come back from StR by something akin to
> booting.

Yes, that's what I meant.

Greetings,
Rafael