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 ?
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 = <®_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 ? .
Hi, I managed to change BSP to supported one in Buildroot as you pointed me.
Changes to menuconfig are:
BR2_LINUX_KERNEL_CUSTOM_GIT=y
BR2_LINUX_KERNEL_CUSTOM_REPO_URL="https://github.com/Freescale/linux-fslc.git"
BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="4.14-2.0.x-imx"
Now # cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq returns 792000 and most things appear to work with BSP Kernel version 4.14.159 built with Buldroot.
Thanks for your help !.
Best regards,
Marcin Nowicki
Hello
Unfortunately, you are using an unsupported BSP. We cannot help you properly. What I suggest is to use an example of our Linux API to change the CPU frequency. However, the implementation is on your own. If you are willing to have professional assistance. I suggest you contact our professional service support portal.
Professional Support for Processors and Microcontrollers | NXP
Best regards,
Diego.
I guess BSP is implemented directly into Linux Kernel which is open-source.
Could you tell me which Kernel version similar to 4.14 is poperly supported by NXP so It doesn't have any issues with the newest IMX6ULL processor models ? By the way 4.14 is working pretty well apart from changing clock rate.
Could you also tell me more about the Linux API ?
Hello,
The most similar version that we have is Linux 4.14.98. You could use our BSP as a reference.
Best regards,
Diego.