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How to change IMX6ULL frequency from 528Mhz to 792Mhz

Question asked by Marcin Nowicki on Jan 31, 2020
Latest reply on Feb 4, 2020 by Marcin Nowicki

Hi,

I am running custom linux build with Buildroot(kernel version 4.14.154) on my custom designed board. Everything works(all peripheralls and user-sapce app) except I cannot change processor frequency to 792 Mhz after linux boots up.

I followed instructions on :

How can I change CPU frequency on i.MX6Q ?

How to change the CPU frequency from 800Mhz to 1GHz ? 

Change CPU frequency 

 

My CPU phandle in device tree :

&cpu0 {
    compatible = "arm,cortex-a7";
    device_type = "cpu";
    reg = <0>;
    clock-frequency = <792000000>;
    clock-latency = <61036>; /* two CLK32 periods */
    operating-points = <
        /* kHz    uV */
        792000    1175000
        528000    1175000
        396000    1025000
        198000    950000
    >;
    fsl,soc-operating-points = <
        /* KHz    uV */
        792000    1175000
        528000    1175000
        396000    1175000
        198000    1175000
    >;
    arm-supply = <&reg_arm>;
    soc-supply = <&reg_soc>;
    dc-supply = <&reg_gpio_dvfs>;
};

In rcS script I have:
echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 792000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

 

Unfortunately cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq returns 528000 so I guess CPU still runs on this clock.

Interestingly cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq returns 792000.

It is exactly MCIMX6Y2CVM08AB processor model capable of running on this frequency.

Does anyone know how to change IMX6ULL CPU frequency ? .

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