rk3368 CPU动态调频与温度保护

news/2024/10/21 9:59:13/

Platform: RK3368

OS: Android 6.0

Kernel: 3.10.0

rk3368采用cpufreq进行CPU频率调节，但同时又做了过温保护和温度限制频率。

1. 过温保护

驱动位于kernel/drivers/thermal/rockchip_thermal.c
dts定义:

tsadc: tsadc@ff280000 {compatible = "rockchip,rk3368-tsadc";reg = <0x0 0xff280000 0x0 0x100>;interrupts = <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>;clocks = <&clk_tsadc>, <&clk_gates20 0>;rockchip,grf = <&grf>;rockchip,cru = <&cru>;rockchip,pmu = <&pmu>;clock-names = "tsadc", "apb_pclk";clock-frequency = <32000>;resets = <&reset RK3368_SRST_TSADC_P>;reset-names = "tsadc-apb";//pinctrl-names = "default";//pinctrl-0 = <&tsadc_int>;#thermal-sensor-cells = <1>;hw-shut-temp = <120000>;status = "disabled";};

可以看到当前hw-shut-temp = <120000>;也就是温度大于120度就会触发过温保护,强制关机。
查看当前CPU温度:

#cat /sys/rockchip_thermal/temp

2. CPU动态调频(DVFS)

Linux内部共有五种对频率的管理策略userspace，conservative，ondemand，powersave 和 performance.可以根据负载进行频率提升和降低。

查看支持的governors
# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
conservative ondemand userspace powersave interactive performance

DVFS的dts定义:

dvfs {vd_arm: vd_arm {regulator_name = "vdd_arm";suspend_volt = <1000>; //mVpd_core {clk_core_b_dvfs_table: clk_core_b {operating-points = </* KHz    uV */312000 1200000504000 1200000816000 12000001008000 1200000>;status = "okay";cluster = <0>;temp-limit-enable = <1>;target-temp = <80>;min_temp_limit = <216000>;normal-temp-limit = </*delta-temp    delta-freq*/3	960006	1440009	19200015	384000>;performance-temp-limit = </*temp    freq*/100     816000>;lkg_adjust_volt_en = <1>;channel = <0>;tsadc-ch = <0>;def_table_lkg = <25>;min_adjust_freq = <216000>;lkg_adjust_volt_table = </*lkg(mA)  volt(uV)*/0         25000>;pvtm_min_temp = <25>;};clk_core_l_dvfs_table: clk_core_l {operating-points = </* KHz    uV */312000 1200000504000 1200000816000 12000001008000 1200000>;status = "okay";cluster = <1>;temp-limit-enable = <1>;target-temp = <80>;min_temp_limit = <216000>;normal-temp-limit = </*delta-temp    delta-freq*/3	960006	1440009	19200015	384000>;performance-temp-limit = </*temp    freq*/100     816000>;lkg_adjust_volt_en = <1>;channel = <0>;tsadc-ch = <0>;def_table_lkg = <25>;min_adjust_freq = <216000>;lkg_adjust_volt_table = </*lkg(mA)  volt(uV)*/0         25000>;pvtm_min_temp = <25>;};};};

可以看到里面定义了大核和小核的两种限制模式，normal-temp-limit和performance-temp-limit。performance模式中，当温度高于80则频率限制在816000。而在normal模式中，则是每当温度上升delta-temp，则频率降低delta-freq，直到降到min_temp_limit为止。

实现代码位于:
arch/arm/mach-rockchip/dvfs.c
驱动初始化了一个工作队列dvfs_temp_limit_work_func，每隔HZ/10执行一次。主要任务是根据当前温度对temp_limit_rate进行修改。从而让dvfs_get_limit_rate返回的是限频的值。

系统默认为normal模式，在init.rc中写入的：

    # set temperature control policy as normal modewrite /sys/module/rockchip_pm/parameters/policy 1

查看及修改当前电源策略:

# cat /sys/module/rockchip_pm/parameters/policy
# echo "1">/sys/module/rockchip_pm/parameters/policy