Re: [RFC][PATCH 00/11] Android PM extensions

Pavel Machek
2009-02-02T11:55:18Z

Hi!

> However, I think that what we are used to call a sleep (or suspend) state is
> really a power off state for cell phone people. So lets define what we're
> talking about.
>
> Sleep states (suspend to RAM, hibernation) are the states of the whole system
> in which no instructions are executed by the processor(s). The
> difference

s/processor(s)/CPU/.

Even in PC, you have keyboard controller running while sleeping. On
cellphone, you have some kind of pmu chip + GSM chip running. So
cellphone actually _is_ useful even when CPU is sleeping.

> between a sleep state and the power off state is that in a sleep state we have
> some application context saved (in memory or in a storage device) and
> (in principle) after the system goes back to the working state, the
> applications can continue doing do whatever they had been doing before the
> system was put into the sleep state.
>
> If instructions are executed by the processor(s), the system is in the working
> state.

ACK.

> Well, I think that sleep states are not really useful in cell phones. Useful
> is the ability to put all devices into low power states separately and as
> needed (eg. after a period of inactivity). IOW, the system as a
> whole is

No, it does not work like that. Cellphone with sleeping CPU
(suspended-to-RAM) is still very useful.
Pavel
--
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