Re: So, what's the status on the recent patches here?

Pavel Machek
2006-08-31T12:04:54Z

Hi!

> > We may have confusion here.
> >
> > On PC, it is definitely not possible to enter sleep state
> > between frames of video... because video is powered off.
> >
> > On PC, sleep states are *system* sleep states. CPU sleep
> > states exist, too, but that's in-kernel implementation
> > detail. They are called C1..C4.
> ---
>
> Well, we have some hardware where we can sleep everything but
> memory and some where we can also leave the display active (and
> backlit). In fact, however, today the latency for going to sleep
> is too great to do so between frames, so we just do a wait there.
> We would LIKE to be able to sleep there at some point in the
> future and would prefer a power model that made that cleanly
> part of a continuum of operating points.
>
> However, we definitely DO sleep (with self-refreshing RAM) during
> relatively short periods, with the wakeup resulting from an
> interrupt from the RTC (which is self-powered and is set
> to timeout at the next scheduled timer when we go to sleep)
> or another hardware interrupt. We think of this as a system-level
> sleep state.
>
> I'm not sure how you distinguish between a "system" sleep state
> and a "CPU" sleep state - seems like there's a collection of
> things that can be shut down or not; except for true OFF, there's
> always something on.

Well, even in "true OFF", RTC keeps ticking. And in "disk" state
(swsusp), machine is basically "true OFF" but it still retains state.

Pavel

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