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

[Matthew Locke <matthew.a.locke@comcast.net>]

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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