[maemo-developers] Frequencies scaling with OS2008

[From: Frantisek Dufka]

Klaus.K Pedersen (Nokia-M/Helsinki) wrote:
> On Wed, 2008-01-02 at 13:30 +0100, ext Frantisek Dufka wrote:
>> Igor Stoppa wrote:
>>> On Mon, 2007-12-31 at 17:37 +0100, ext Frantisek Dufka wrote:
>>>> Igor Stoppa wrote:
>>>>> Having the audio path open, but no dsp tack loaded (arm audio) sets the
>>>>> clock to 400MHz.
>>>> Interesting, so, umm, there is way to play audio from ARM side directly? 
>>> Mixing is still happening on DSP.
>>>
>> I see so DSP is running fully but there is no dynamic task loaded so the 
>> multimedia requirements are low and it can run at 400/133, right? 
> 
> So what you are seeing is that the "DSP task policy" is active even
> though there are no dynamic dsp task loaded?
> 

Just an update/explanation. I was not fuly aware of how it works. The 
most important difference here that I missed previously is the term 
'dynamic dsp task'. I was not aware that there are also 'static' dsp 
tasks. They look same from userspace but are linked statically to dsp 
bios (?) and the clock policy ignores them (on purpose).

So the pcm0/pcm1 dsp tasks are static but pcm2 is dynamic. Therefore 
uncompressed audio output via pcm0/1 leaves the clock at 400 but same 
output via pcm2 drops clock to 330. So maybe this is a bug and I should 
report it in bugzilla? Maybe Real audio should use pcm0 or 1 or pcm2 
should not be dynamic task?

Frantisek