Re: nokia 770 [was Re: community PM requirements/issues and PowerOP]

Matthew Locke
2006-12-13T21:27:35Z

On Dec 12, 2006, at 12:00 PM, David Brownell wrote:

> On Tuesday 19 September 2006 11:25 am, Pavel Machek wrote:
>>
>> Could you perhaps provide list of operating points for 770? It would
>> help understanding a bit, I'd say.
>
> If there was a followup here, I missed it ...

I think there was some sort of followup but I don't think it
explictly listed the operating point values.
>
> ISTR that it doesn't use (formal) operating points, and that a lot
> of the
> basic SOC power savings (vs powering off the display or wifi) come
> from a
> different kind of mechanism entirely. Namely, a combination of
> dynamic
> tick with a modified system idle task, which enters one of the OMAP
> low
> power modes during those long periods between clock ticks or other
> irqs.
>
> That's one of the standard power saving schemes used on OMAP1
> platforms
> with Linux.

Well sure but I think this discussion was about using the 770 as a
specific example of operating point values. Here are the operating
points used on omap1. The board specific part is just whether or not
the board has a scalable voltage regulator. Omap1 has a fairly
simple operating point definition and is, of course, not the latest h/w.

This table comes from the DPM implementation on OMAP1 and is
expressed as dividers.

Name Voltage, DPLL multiplier, DPLL divider, cpu divider, tc divider
(mem bus).

192 1300 16 1 1 2
168 1300 14 1 1 2
84 1300 14 1 2 2
84-1.1v 1050 14 1 2 2
60 1300 5 1 1 1
60-1.1v 1050 5 1 1 1
sleep-168 1300 14 1 0 -1
sleep-60 1300 1 2 0 2

Several other parameters could be added such as dsp and dsp mmu if
one wanted to do more aggressive power management. btw, the
parameter names I list above are from memory so I might have the
order mixed up but you get the idea.

The dpm utilities on sf.net also include 8 example operating points
for pxa272. The operating point definition on pxa has ~5 parameters
including voltage, cpu frequency and other clocks.

>
> - Dave
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