唤醒流程之背光控制

来源：互联网发布：贸易数据编辑：程序博客网时间：2024/05/07 08:34

本文基于rk3128平台代码分析；

唤醒流程中控制背光的流程如下：

1、frameworks/base/services/core/java/com/android/server/display/DisplayPowerController.java

private final LightsManager mLights

mLights = LocalServices.getService(LightsManager.class);//获得LightServer

mPowerState = new DisplayPowerState(mBlanker,
mLights.getLight(LightsManager.LIGHT_ID_BACKLIGHT),
new ColorFade(Display.DEFAULT_DISPLAY)); \\获得lightserver实例初始化DisplayPowerState结构体

mPowerState.setScreenState(state); //在DisplayPowerState实例中调用方法进行brightness的控制

PS：LightServer中还提供其他light的控制，如下为举例

mButtonLight = mLights.getLight(LightsManager.LIGHT_ID_BUTTONS);

mButtonLight.setBrightness(0);

2、frameworks/base/services/core/java/com/android/server/display/DisplayPowerState.java

/**
127 * Sets whether the screen is on, off, or dozing.
128 */
129 public void setScreenState(int state) {
130 if (mScreenState != state) {
131 if (DEBUG) {
132 Slog.d(TAG, "setScreenState: state=" + state);
133 }
134
135 mScreenState = state;
136 mScreenReady = false;
137 scheduleScreenUpdate();
138 }
139 }

根据屏幕状态不同，自动设置屏幕开关的方法，内部包括亮度设置等，本文只关注亮度设置；

这里更新mScreenState的状态后，通过scheduleScreenUpdate方法进行一系列的设置；

最终调用：mBacklight.setBrightness(backlight);进行设置 // mBacklight为上面 mLights.getLight(LightsManager.LIGHT_ID_BACKLIGHT)获得的Light实例

3、frameworks/base/services/core/java/com/android/server/lights/LightsService.java

第二部调用的是本文件内部类private final class LightImpl extends Light中的

public void setBrightness(int brightness)；

最终调用jni层：

setLight_native(mNativePointer, mId, color, mode, onMS, offMS, brightnessMode);

4、frameworks/base/services/core/jni/com_android_server_lights_LightsService.cpp

通过hw_get_module(LIGHTS_HARDWARE_MODULE_ID, (hw_module_t const**)&module);获得相关的模块

最终调用hal层的devices->lights[light]->set_light(devices->lights[light], &state);接口对背光进行设置；

5、hardware/rockchip/liblights/lights.cpp（瑞芯微私有hal，通过LIGHTS_HARDWARE_MODULE_ID查找）

查看对应代码，最终实际是调用write_int(BACKLIGHT_PATH, brightness);向sysfs中背光文件进行写入进行设置；

BACKLIGHT_PATH定义：#define BACKLIGHT_PATH "/sys/class/backlight/rk28_bl/brightness"

6、接下来进入内核驱动，待续

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