Re: [PATCH] implement pm_ops.valid for everybody

Scott E. Preece
2007-03-22T13:44:02Z

| 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.

scott
--
scott preece
motorola mobile devices, il67, 1800 s. oak st., champaign, il 61820
e-mail: preece@motorola.com fax: +1-217-384-8550
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