Re: [Gumstix-users] ARM-Core CPU Freuqency

[Thorsten B. <tho...@go...>]

Søren Steen Christensen wrote:
> 
> Hi Thorsten,
> 
>> - Can it be done in the bootloader ? How low can it be set ?
> You can set the variable mpurate in u-boot. In theory you can set it all
> the
> way down to 0MHz. 
> 
> In practice 125MHz I the lowest officially supported operation
> frequency...
> 
> Best regards - Good luck
>   Søren
> 
> ---
> SSC Solutions ApS - Denmark - www.ssc-solutions.dk 
> 
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OK - I did in the u-boot environment at startup

setenv mpurate 125; saveenv; reset;

After fw-printenv I also get now :

...
mpurate=125


BUT when I call : 

cat /proc/cpuinfo

I still get 499 BogoMips

So it seems that the CPU fruqency seems not to be lowered.

I'm also monitoring the power consumption of the overo fire board (on a
chestnut mainboard) (and would like to lower it to the "min") - and it seems
that the board power consumption seems not be changed - still - without
monitor and usb peripherals around 450mA at 5V.

Also the boot-up time seems not to be decreased due to a lower clock speed.

Like that I assume my approach for manipulating the cpu-frequency wasn't
successful. Maybe there are better way to monitor this (please let me know).
Anyway I hope that someone can help me to get things going in order to lower
clock frequency of the device and save power.

Furtheron - if there is a way to lower the cpu frequency at runtime - I
would be highl interested - I read about something like "cpufreq" but
couldn't find this tool (in the packages ...)





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