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 :
My CPU phandle in device tree :
compatible = "arm,cortex-a7";
device_type = "cpu";
reg = <0>;
clock-frequency = <792000000>;
clock-latency = <61036>; /* two CLK32 periods */
operating-points = <
/* kHz uV */
fsl,soc-operating-points = <
/* KHz uV */
arm-supply = <®_arm>;
soc-supply = <®_soc>;
dc-supply = <®_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 ? .