[maemo-developers] Frequencies scaling with OS2008

[From: Frantisek Dufka]

Krischan Keitsch wrote:
> I was wondering if the device really needs to run at 300MHz (220MHz dsp) for 
> mp3 playback? Is the max dsp power needed for such a task? Or would 220MHz 
> (177MHz dsp) or 165MHz (85MHz dsp) be sufficient? Would a lower dsp scaling 
> save even more battery?

Well, yes it looks a bit simplistic now. Even if you play audio decoded 
by ARM cpu (ogg, real audio) it seems to lock ARM core to 330 and dsp to 
220Mhz. I suppose it is because you need pcm dsp task running for audio 
output and any active dsp task locks it to 220Mhz (and thus cpu to 330). 
I wonder if it is just simple implementation that can be tuned in next 
firmwares or there is some fundamental problem (like changing dsp clock 
of already running dsp task may break it so it is hardcoded to 220).

Frantisek