Android 11 低电量自动关机失效

Android 11 低电量自动关机

概述

安卓系统设计了低电关机功能，旨在当手机电池电量过低时自动关机，以保护手机硬件和数据安全。该功能由以下几个部分组成：

• 电池电量监测: 安卓系统通过 BatteryService 组件持续监测电池电量。BatteryService会从底层获取电池电量信息，并根据预设的阈值判断电池电量是否过低。
• 低电量警告: 当电池电量低于预设的警告阈值时，BatteryService会触发低电量警告。低电量警告通常会以弹窗或声音提示的形式通知用户。
• 低电关机: 当电池电量低于预设的关机阈值时，BatteryService会触发低电关机。低电关机前，系统会提示用户保存数据并关闭正在运行的应用。

基于RK3568 Android 11 系统开发过程中, 移植了电源和电池相关的驱动后, 测试发现低电自动关机的功能失效了.

分析

首先, 从dumpsys 中看下当前电池的一些状态信息(PS: 新版本的内容呈现有所不同):

• dumpsys battery

  battery
  Current Battery Service state:
    AC powered: false
    USB powered: false
    Wireless powered: false
    Max charging current: 0
    Max charging voltage: 0
    Charge counter: 0
    status: 3
    health: 2
    present: true
    level: 0
    scale: 100
    voltage: 11
    current: 640
    temperature: 308
    technology: Li-ion
  

• 处理低电关机的关键代码: frameworks/base/services/core/java/com/android/server/BatteryService.java

      private void processValuesLocked(boolean force) {
       
          boolean logOutlier = false;
          long dischargeDuration = 0;
  
          mBatteryLevelCritical =
              mHealthInfo.batteryStatus != BatteryManager.BATTERY_STATUS_UNKNOWN
              && mHealthInfo.batteryLevel <= mCriticalBatteryLevel;
          if (mHealthInfo.chargerAcOnline) {
       
              mPlugType = BatteryManager.BATTERY_PLUGGED_AC;
          } else if (mHealthInfo.chargerUsbOnline) {
       
              mPlugType = BatteryManager.BATTERY_PLUGGED_USB;
          } else if (mHealthInfo.chargerWirelessOnline) {
       
              mPlugType = BatteryManager.BATTERY_PLUGGED_WIRELESS;
          } else {
       
              mPlugType = BATTERY_PLUGGED_NONE;
          }
  
          if (DEBUG) {
       
              Slog.d(TAG, "Processing new values: "
                      + "info=" + mHealthInfo
                      + ", mBatteryLevelCritical=" + mBatteryLevelCritical
                      + ", mPlugType=" + mPlugType);
          }
  
          // Let the battery stats keep track of the current level.
          try {
       
              mBatteryStats.setBatteryState(mHealthInfo.batteryStatus, mHealthInfo.batteryHealth,
                      mPlugType, mHealthInfo.batteryLevel, mHealthInfo.batteryTemperature,
                      mHealthInfo.batteryVoltage, mHealthInfo.batteryChargeCounter,
                      mHealthInfo.batteryFullCharge,
                      mHealthInfo2p1.batteryChargeTimeToFullNowSeconds);
          } catch (RemoteException e) {
       
              // Should never happen.
          }
  
          shutdownIfNoPowerLocked();
          shutdownIfOverTempLocked();
          //....................
      }    
      private void shutdownIfNoPowerLocked() {
       
          // shut down gracefully if our battery is critically low and we are not powered.
          // wait until the system has booted before attempting to display the shutdown dialog.
          if (shouldShutdownLocked()) {
       
              mHandler.post(new Runnable() {
       
                  @Override
                  public void run() {
       
                      if (mActivityManagerInternal.isSystemReady()) {
       
                          Intent intent = new<