CPU

1 S5P4418/S5P6818 降低CPU频率

1.1 Method 1

The following command is used to temporarily limit the maximum CPU frequency to 1GHz: echo 1000000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

1.2 Method 2

Modify the kernel source code:

arch/arm/plat-s5p4418/nanopi2/device.c

Delete the unwanted frequencies in the following array:

static unsigned long dfs_freq_table[][2] = {
    { 1400000, 1200000, },
    { 1200000, 1120000, },
    { 1000000, 1040000, },
    {  800000, 1000000, },
    {  700000,  940000, },
    {  600000,  940000, },
    {  500000,  940000, },
    {  400000,  940000, },
};

2 获取CPU温度

读取以下文件获得当前的CPU温度：
S5P4418/S5P6818:
/sys/class/hwmon/hwmon0/device/temp_label
Allwinner H3/H5/A64:
/sys/class/thermal/thermal_zone0/temp
RK3399:
/sys/class/thermal/thermal_zone0/temp