Android P指示灯调节代码逻辑

指示灯代码逻辑查看与定义：
默认当低电量时候，指示灯亮灭是1s-1s 的切换； 根据产品定义反馈，切换的太过频繁，需要调整修改。
当电量较多时候，不处于低电量时候，系统处于正常的battery实现逻辑中，而当电量低于15之后，电量切换为setBrightness和setColor模式下，出现了闪光灯一直切换的情况。所以其闪烁未按照现有的软件逻辑执行。

LightsService.java

private void setLightLocked(int color, int mode, int onMS, int offMS, int brightnessMode) {
            if (shouldBeInLowPersistenceMode()) {
                brightnessMode = BRIGHTNESS_MODE_LOW_PERSISTENCE;
            } else if (brightnessMode == BRIGHTNESS_MODE_LOW_PERSISTENCE) {
                brightnessMode = mLastBrightnessMode;
            }

            if (!mInitialized || color != mColor || mode != mMode || onMS != mOnMS ||
                    offMS != mOffMS || mBrightnessMode != brightnessMode) {
                if (DEBUG) Slog.v(TAG, "setLight #" + mId + ": color=#"
                        + Integer.toHexString(color) + ": brightnessMode=" + brightnessMode);
                mInitialized = true;
                mLastColor = mColor;
                mColor = color;
                mMode = mode;
                mOnMS = onMS;
                mOffMS = offMS;
                mBrightnessMode = brightnessMode;
                Trace.traceBegin(Trace.TRACE_TAG_POWER, "setLight(" + mId + ", 0x"
                        + Integer.toHexString(color) + ")");
                try {
                    setLight_native(mId, color, mode, onMS, offMS, brightnessMode);
                } finally {
                    Trace.traceEnd(Trace.TRACE_TAG_POWER);
                }
            }
        }

设置执行的主要函数是：setLight_native

    static native void setLight_native(int light, int color, int mode,
            int onMS, int offMS, int brightnessMode);

根据Jni函数设置找到对应的文件：
frameworks/base/services/core/jni/com_android_server_lights_LightsService.cpp

static void setLight_native(
        JNIEnv* /* env */,
        jobject /* clazz */,
        jint light,
        jint colorARGB,
        jint flashMode,
        jint onMS,
        jint offMS,
        jint brightnessMode) {

    if (!validate(light, flashMode, brightnessMode)) {
        return;
    }

    //连接LightHal节点
    sp<ILight> hal = LightHal::associate();

    if (hal == nullptr) {
        return;
    }

    Type type = static_cast<Type>(light);
    LightState state = constructState(
        colorARGB, flashMode, onMS, offMS, brightnessMode);

    {
        android::base::Timer t;
        Return<Status> ret = hal->setLight(type, state);
        processReturn(ret, type, state);
        if (t.duration() > 50ms) ALOGD("Excessive delay setting light");
    }
}

static LightState constructState(
        jint colorARGB,
        jint flashMode,
        jint onMS,
        jint offMS,
        jint brightnessMode){
    Flash flash = static_cast<Flash>(flashMode);
    Brightness brightness = static_cast<Brightness>(brightnessMode);

    LightState state{};

    if (brightness == Brightness::LOW_PERSISTENCE) {
        state.flashMode = Flash::NONE;
    } else {
        // Only set non-brightness settings when not in low-persistence mode
        state.flashMode = flash;
        state.flashOnMs = onMS;
        state.flashOffMs = offMS;
    }

    state.color = colorARGB;
    state.brightnessMode = brightness;

    return state;
}

此处插一句：刚刚总是查找android.hardware.light.V2_0.Flash和android.hardware/light.V2_0.Brightnes

import android.hardware.light.V2_0.Flash;
import android.hardware.light.V2_0.Brightness;

此文件的定义在jni中也同样找到：

using Brightness = ::android::hardware::light::V2_0::Brightness;
using Flash      = ::android::hardware::light::V2_0::Flash;
using ILight     = ::android::hardware::light::V2_0::ILight;
using LightState = ::android::hardware::light::V2_0::LightState;
using Status     = ::android::hardware::light::V2_0::Status;
using Type       = ::android::hardware::light::V2_0::Type;

找到匹配文件点：
hardware/interfaces/light/2.0/types.hal

enum Flash : int32_t {
    /**
     * Keep the light steady on or off.
     */
    NONE,

    /**
     * Flash the light at specified rate.
     */
    TIMED,

    /**
     * Flash the light using hardware assist.
     */
    HARDWARE,
};

其对应的外部接口函数为：hardware\interfaces\light\2.0\ILight.hal

package android.hardware.light@2.0;

interface ILight {

    /**
     * Set the provided lights to the provided values.
     *
     * @param type logical light to set
     * @param state describes what the light should look like.
     * @return status result of applying state transformation.
     */
    setLight(Type type, LightState state) generates (Status status);

    /**
     * Discover what indicator lights are available.
     *
     * @return types list of available lights
     */
    getSupportedTypes() generates (vec<Type> types);

};

在\hardware\interfaces\light\2.0\default\Light.cpp文件中的实现过程是：

// Methods from ::android::hardware::light::V2_0::ILight follow.
Return<Status> Light::setLight(Type type, const LightState& state)  {
    auto it = mLights.find(type);

    if (it == mLights.end()) {
        return Status::LIGHT_NOT_SUPPORTED;
    }

    light_device_t* hwLight = it->second;

    light_state_t legacyState {
        .color = state.color,
        .flashMode = static_cast<int>(state.flashMode),
        .flashOnMS = state.flashOnMs,
        .flashOffMS = state.flashOffMs,
        .brightnessMode = static_cast<int>(state.brightnessMode),
    };

    int ret = hwLight->set_light(hwLight, &legacyState);

    switch (ret) {
        case -ENOSYS:
            return Status::BRIGHTNESS_NOT_SUPPORTED;
        case 0:
            return Status::SUCCESS;
        default:
            return Status::UNKNOWN;
    }
}

在lights.c文件hardware/qcom/display/liblight/lights.c:
不同的模式下的闪光灯赋予均赋予给set_light 处理；

/******************************************************************************/

/**
 * module methods
 */

/** Open a new instance of a lights device using name */
static int open_lights(const struct hw_module_t* module, char const* name,
        struct hw_device_t** device)
{
    int (*set_light)(struct light_device_t* dev,
            struct light_state_t const* state);

    if (0 == strcmp(LIGHT_ID_BACKLIGHT, name)) {
        set_light = set_light_backlight;
    } else if (0 == strcmp(LIGHT_ID_BATTERY, name))
        set_light = set_light_battery;
    else if (0 == strcmp(LIGHT_ID_NOTIFICATIONS, name))
        set_light = set_light_notifications;
    else if (0 == strcmp(LIGHT_ID_BUTTONS, name)) {
        if (!access(BUTTON_FILE, F_OK)) {
          // enable light button when the file is present
          set_light = set_light_buttons;
        } else {
          return -EINVAL;
        }
    }
    else if (0 == strcmp(LIGHT_ID_ATTENTION, name))
        set_light = set_light_attention;
    else
        return -EINVAL;

    pthread_once(&g_init, init_globals);

    struct light_device_t *dev = malloc(sizeof(struct light_device_t));

    if(!dev)
        return -ENOMEM;

    memset(dev, 0, sizeof(*dev));

    dev->common.tag = HARDWARE_DEVICE_TAG;
    dev->common.version = LIGHTS_DEVICE_API_VERSION_2_0;
    dev->common.module = (struct hw_module_t*)module;
    dev->common.close = (int (*)(struct hw_device_t*))close_lights;
    dev->set_light = set_light;

    *device = (struct hw_device_t*)dev;
    return 0;
}

而我们现在主要是查找关于battery电量的闪烁：

static void
handle_speaker_battery_locked(struct light_device_t* dev)
{
    if (is_lit(&g_battery)) {
        set_speaker_light_locked(dev, &g_battery);
    } else {
        set_speaker_light_locked(dev, &g_notification);
    }
}

static int
set_light_battery(struct light_device_t* dev,
        struct light_state_t const* state)
{
    pthread_mutex_lock(&g_lock);
    g_battery = *state;
    handle_speaker_battery_locked(dev);
    pthread_mutex_unlock(&g_lock);
    return 0;
}

static int
set_light_notifications(struct light_device_t* dev,
        struct light_state_t const* state)
{
    pthread_mutex_lock(&g_lock);
    g_notification = *state;
    handle_speaker_battery_locked(dev);
    pthread_mutex_unlock(&g_lock);
    return 0;
}

进而直接可以找到其实现过程：

static int
set_speaker_light_locked(struct light_device_t* dev,
        struct light_state_t const* state)
{
    int red, green, blue;
    int blink;
    int onMS, offMS;
    unsigned int colorRGB;

    if(!dev) {
        return -1;
    }

    switch (state->flashMode) {
        case LIGHT_FLASH_TIMED:
            onMS = state->flashOnMS;
            offMS = state->flashOffMS;
            break;
        case LIGHT_FLASH_NONE:
        default:
            onMS = 0;
            offMS = 0;
            break;
    }

    colorRGB = state->color;

#if 0
    ALOGD("set_speaker_light_locked mode %d, colorRGB=%08X, onMS=%d, offMS=%d\n",
            state->flashMode, colorRGB, onMS, offMS);
#endif

    red = (colorRGB >> 16) & 0xFF;
    green = (colorRGB >> 8) & 0xFF;
    blue = colorRGB & 0xFF;

    if (onMS > 0 && offMS > 0) {
        /*
         * if ON time == OFF time
         *   use blink mode 2
         * else
         *   use blink mode 1
         */
        if (onMS == offMS)
            blink = 2;
        else
            blink = 1;
    } else {
        blink = 0;
    }

    if (blink) {
        if (red) {
            if (write_int(RED_BLINK_FILE, blink))
                write_int(RED_LED_FILE, 0);
        }
        if (green) {
            if (write_int(GREEN_BLINK_FILE, blink))
                write_int(GREEN_LED_FILE, 0);
        }
        if (blue) {
            if (write_int(BLUE_BLINK_FILE, blink))
                write_int(BLUE_LED_FILE, 0);
        }
    } else {
        write_int(RED_LED_FILE, red);
        write_int(GREEN_LED_FILE, green);
        write_int(BLUE_LED_FILE, blue);
    }

    return 0;
}

如果不是按照时间闪烁，则直接on/off 时间直接均赋予为0.

那么可以知道现在指示灯闪烁基本是芯片默认设置。