如何使用QCS8550的 thermal-engine,比如调整风扇的强度?

开开心心过大 2024-07-26 15:58:34

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weixin_38498942 2024-07-29

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由于各个厂商在thermal governor和硬件上的差异（sensor的排布不同），thermal zone中的温度sensor、cooling devices的设备树配置也有所不同。kernel document总结了几种thermal zone设备树配置示例。

#include <dt-bindings/thermal/thermal.h>

/*cpufreq cooling device-passive被动冷却*/
cpus {
    /*
     * Here is an example of describing a cooling device for a DVFS
     * capable CPU. The CPU node describes its four OPPs.
     * The cooling states possible are 0..3, and they are
     * used as OPP indexes. The minimum cooling state is 0, which means
     * all four OPPs can be available to the system. The maximum
     * cooling state is 3, which means only the lowest OPPs (198MHz@0.85V)
     * can be available in the system.
     */
    /*  */
    cpu0: cpu@0 {
        ...
        operating-points = <
            /* kHz    uV */
            970000  1200000
            792000  1100000
            396000  950000
            198000  850000
        >;
        cooling-min-level = <0>;/* 说明四组OPPs都可用 */
        cooling-max-level = <3>;/* 说明OPPs中只有频率最低的那一组可用（198MHz@0.85V） */
        #cooling-cells = <2>; /* min followed by max */
    };
    ...
};

/*风扇控制器-active主动冷却*/
/*一个通过i2c总线1控制的风扇设备fan0，地址0x48，有10个冷却等级*/
&i2c1 {
    ...
    /*
     * A simple fan controller which supports 10 speeds of operation
     * (represented as 0-9).
     */
    fan0: fan@0x48 {
        ...
        cooling-min-level = <0>;
        cooling-max-level = <9>;/* 10 cooling states */
        #cooling-cells = <2>; /* min followed by max */
    };
};

/*温度传感器IC*/
/*ADC sensor（bandgap0），地址0x0000ED00，用来监视'cpu-thermal'的温度*/
ocp {
    ...
    /*
     * A simple IC with a single bandgap temperature sensor.
     */
    bandgap0: bandgap@0x0000ED00 {
        ...
        #thermal-sensor-cells = <0>;
    };
};

thermal-zones {
    cpu_thermal: cpu-thermal {
        polling-delay-passive = <250>; /* milliseconds */
        polling-delay = <1000>; /* milliseconds */

        thermal-sensors = <&bandgap0>;

        trips {
            cpu_alert0: cpu-alert0 {
                temperature = <90000>; /* millicelsius */
                hysteresis = <2000>; /* millicelsius */
                type = "active";
            };
            cpu_alert1: cpu-alert1 {
                temperature = <100000>; /* millicelsius */
                hysteresis = <2000>; /* millicelsius */
                type = "passive";
            };
            cpu_crit: cpu-crit {
                temperature = <125000>; /* millicelsius */
                hysteresis = <2000>; /* millicelsius */
                type = "critical";
            };
        };

        cooling-maps {
            map0 {
                trip = <&cpu_alert0>;
                cooling-device = <&fan0 THERMAL_NO_LIMIT 4>;/* 温度超过cpu_alert0时，等级0-4 */
            };
            map1 {
                trip = <&cpu_alert1>;
                cooling-device = <&fan0 5 THERMAL_NO_LIMIT>;/* 温度超过cpu_alert1时，等级5-9 */ 
            };
            map2 {
                trip = <&cpu_alert1>;
                cooling-device =
                    <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;/* 所有冷却等级都可以用在cpu_alert1上，即温度在alert1-alert2之间，所有冷却等级可用 */
            };
        };
    };
};