OPP question


john4p

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Feb 29, 2008
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If you set OPP5 as "maximum OPP" does it automatically use OPP3 when you set the cpu speed to 600 MHz?
 
Yes. I don't know the exact frequencies when it changes the OPP (can be found in the sourcecode though), but it only switches to a high OPP when necessary.
 
id be willing to bet the sourcecode overvolts it to opp5 at no more than 850mhz, even though its mostly stable at opp3. so my guess is, thats its a bad idea to just leave it at OPP5, and let the firmware overvolt as necessary
 
okay, now I'm confused... I seem to recall seeing previous posts stating that automatic OPP changes only happened under the newer versions of the kernel.. (including the experimental one, but not the stable one)


What am I missing?


- Neelix
 
Not sure of the context of those posts, but auto OPP adjustment has been present since the OPP setting scripts were added to the firmware. That might have been HF4 or HF5.
 
okay, now I'm confused... I seem to recall seeing previous posts stating that automatic OPP changes only happened under the newer versions of the kernel.. (including the experimental one, but not the stable one)


What am I missing?
You are not missing anythings. Currently OPP switching depends on hardcoded clockrates. Meaning "when <=125MHz, switch to OPP1". The "problem" is that the frequency is currently not automatically changed. The new part in the new kernel is that it will automatically clock down to 125MHz when idle and ramp up again when the cpu power is required. With the old kernel you get 125MHz when switching to low power mode or when manually clocking using the clockrate script. So if you change the default clockrate *AND* the max OPP level to a higher value, you will have this higher OPP used. But if you only change the max OPP but stay at the default clockrate of 600MHz nothing will happen.
 
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