how to set persistent cpu frequency

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how to set persistent cpu frequency

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dluberger
Contributor V

I'm using the imx6 SoloX eval board. During boot, I'm drawing too much current through my ARM Core 1.35V supply.  I see that I can throttle the Core power by limiting the operating frequency, but no matter what I set the cpufreq governor to, it always seems to use "on demand" during boot-up. What I think I need is to have the governor set to powersave during bootup, which will set the core to the lowest available frequency, then I can just change it to on demand later, but how to I make the device use a particular governor during boot?  My hope is that I don't have to mess with a custom kernel build, but I do know there is a "default" option in the kernel menuconfig.  Is there a way to do it via startup script or some persistent setting change?

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b36401
NXP TechSupport
NXP TechSupport

Alternatively you can add changing CPU frequency into startup script.

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dluberger
Contributor V

I was thinking about that but I have no idea how to make the init process do that first thing, plus that wouldn't affect the kernel.  I'm wondering if there's a way to do it through the bootloader (uboot) with a boot script?

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi David

default linux cpufreq governor can be changed using

sect.2.3.3.2.2 Menu Configuration Options attached Linux Manual.

https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt 

Best regards
igor
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dluberger
Contributor V

That's what I mentioned in my post. I wanted to avoid rebuilding the kernel. Is there no other way to do it?

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