Merge "simple AnyMotionDetector" into mnc-dev

services/core/java/com/android/server/AnyMotionDetector.java

@@ -0,0 +1,438 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server;
+
+import android.app.AlarmManager;
+import android.content.BroadcastReceiver;
+import android.content.Intent;
+import android.hardware.Sensor;
+import android.hardware.SensorEvent;
+import android.hardware.SensorEventListener;
+import android.hardware.SensorManager;
+import android.os.Handler;
+import android.os.Message;
+import android.os.PowerManager;
+import android.os.SystemClock;
+import android.util.Slog;
+
+import java.lang.Float;
+
+/**
+ * Determines if the device has been set upon a stationary object.
+ */
+public class AnyMotionDetector {
+    interface DeviceIdleCallback {
+        public void onAnyMotionResult(int result);
+    }
+
+    private static final String TAG = "AnyMotionDetector";
+
+    private static final boolean DEBUG = false;
+
+    /** Stationary status is unknown due to insufficient orientation measurements. */
+    public static final int RESULT_UNKNOWN = -1;
+
+    /** Device is stationary, e.g. still on a table. */
+    public static final int RESULT_STATIONARY = 0;
+
+    /** Device has been moved. */
+    public static final int RESULT_MOVED = 1;
+
+    /** Orientation measurements are being performed or are planned. */
+    private static final int STATE_INACTIVE = 0;
+
+    /** No orientation measurements are being performed or are planned. */
+    private static final int STATE_ACTIVE = 1;
+
+    /** Current measurement state. */
+    private int mState;
+
+    /** Threshold angle in degrees beyond which the device is considered moving. */
+    private final float THRESHOLD_ANGLE = 2f;
+
+    /** Threshold energy above which the device is considered moving. */
+    private final float THRESHOLD_ENERGY = 5f;
+
+    /** The duration of the accelerometer orientation measurement. */
+    private static final long ORIENTATION_MEASUREMENT_DURATION_MILLIS = 2500;
+
+    /** The maximum duration we will collect accelerometer data. */
+    private static final long ACCELEROMETER_DATA_TIMEOUT_MILLIS = 3000;
+
+    /** The interval between accelerometer orientation measurements. */
+    private static final long ORIENTATION_MEASUREMENT_INTERVAL_MILLIS = 5000;
+
+    /**
+     * The duration in milliseconds after which an orientation measurement is considered
+     * too stale to be used.
+     */
+    private static final int STALE_MEASUREMENT_TIMEOUT_MILLIS = 2 * 60 * 1000;
+
+    /** The accelerometer sampling interval. */
+    private static final int SAMPLING_INTERVAL_MILLIS = 40;
+
+    private AlarmManager mAlarmManager;
+    private final Handler mHandler;
+    private Intent mAlarmIntent;
+    private final Object mLock = new Object();
+    private Sensor mAccelSensor;
+    private SensorManager mSensorManager;
+    private PowerManager.WakeLock mWakeLock;
+
+    /** The time when detection was last performed. */
+    private long mDetectionStartTime;
+
+    /** The minimum number of samples required to detect AnyMotion. */
+    private int mNumSufficientSamples;
+
+    /** True if an orientation measurement is in progress. */
+    private boolean mMeasurementInProgress;
+
+    /** The most recent gravity vector. */
+    private Vector3 mCurrentGravityVector = null;
+
+    /** The second most recent gravity vector. */
+    private Vector3 mPreviousGravityVector = null;
+
+    /** Running sum of squared errors. */
+    private RunningSignalStats mRunningStats;
+
+    private DeviceIdleCallback mCallback = null;
+
+    public AnyMotionDetector(AlarmManager am, PowerManager pm, Handler handler, SensorManager sm,
+            DeviceIdleCallback callback) {
+        if (DEBUG) Slog.d(TAG, "AnyMotionDetector instantiated.");
+        mAlarmManager = am;
+        mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, TAG);
+        mHandler = handler;
+        mSensorManager = sm;
+        mAccelSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
+        mMeasurementInProgress = false;
+        mState = STATE_INACTIVE;
+        mCallback = callback;
+        mRunningStats = new RunningSignalStats();
+        mNumSufficientSamples = (int) Math.ceil(
+                ((double)ORIENTATION_MEASUREMENT_DURATION_MILLIS / SAMPLING_INTERVAL_MILLIS));
+        if (DEBUG) Slog.d(TAG, "mNumSufficientSamples = " + mNumSufficientSamples);
+    }
+
+    /*
+     * Acquire accel data until we determine AnyMotion status.
+     */
+    public void checkForAnyMotion() {
+      if (DEBUG) Slog.d(TAG, "checkForAnyMotion(). mState = " + mState);
+        if (mState != STATE_ACTIVE) {
+            mState = STATE_ACTIVE;
+            if (DEBUG) Slog.d(TAG, "Moved from STATE_INACTIVE to STATE_ACTIVE.");
+            mCurrentGravityVector = null;
+            mPreviousGravityVector = null;
+            startOrientationMeasurement();
+        }
+    }
+
+    private void startOrientationMeasurement() {
+        if (DEBUG) Slog.d(TAG, "startOrientationMeasurement: mMeasurementInProgress=" +
+            mMeasurementInProgress + ", (mAccelSensor != null)=" + (mAccelSensor != null));
+
+        if (!mMeasurementInProgress && mAccelSensor != null) {
+            if (mSensorManager.registerListener(mListener, mAccelSensor,
+                    SAMPLING_INTERVAL_MILLIS * 1000)) {
+                mWakeLock.acquire();
+                mMeasurementInProgress = true;
+                mDetectionStartTime = SystemClock.elapsedRealtime();
+                mRunningStats.reset();
+            }
+
+            Message msg = Message.obtain(mHandler, mMeasurementTimeout);
+            msg.setAsynchronous(true);
+            mHandler.sendMessageDelayed(msg, ACCELEROMETER_DATA_TIMEOUT_MILLIS);
+        }
+    }
+
+    private int stopOrientationMeasurementLocked() {
+        if (DEBUG) Slog.d(TAG, "stopOrientationMeasurement. mMeasurementInProgress=" +
+                mMeasurementInProgress);
+        int status = RESULT_UNKNOWN;
+        if (mMeasurementInProgress) {
+            mSensorManager.unregisterListener(mListener);
+            mHandler.removeCallbacks(mMeasurementTimeout);
+            if (mWakeLock.isHeld()) {
+                mWakeLock.release();
+            }
+            long detectionEndTime = SystemClock.elapsedRealtime();
+            mMeasurementInProgress = false;
+            mPreviousGravityVector = mCurrentGravityVector;
+            mCurrentGravityVector = mRunningStats.getRunningAverage();
+            if (DEBUG) {
+                Slog.d(TAG, "mRunningStats = " + mRunningStats.toString());
+                String currentGravityVectorString = (mCurrentGravityVector == null) ?
+                        "null" : mCurrentGravityVector.toString();
+                String previousGravityVectorString = (mPreviousGravityVector == null) ?
+                        "null" : mPreviousGravityVector.toString();
+                Slog.d(TAG, "mCurrentGravityVector = " + currentGravityVectorString);
+                Slog.d(TAG, "mPreviousGravityVector = " + previousGravityVectorString);
+            }
+            mRunningStats.reset();
+            status = getStationaryStatus();
+            if (DEBUG) Slog.d(TAG, "getStationaryStatus() returned " + status);
+            if (status != RESULT_UNKNOWN) {
+                if (DEBUG) Slog.d(TAG, "Moved from STATE_ACTIVE to STATE_INACTIVE. status = " +
+                        status);
+                mState = STATE_INACTIVE;
+            } else {
+                /*
+                 * Unknown due to insufficient measurements. Schedule another orientation
+                 * measurement.
+                 */
+                if (DEBUG) Slog.d(TAG, "stopOrientationMeasurementLocked(): another measurement" +
+                        " scheduled in " + ORIENTATION_MEASUREMENT_INTERVAL_MILLIS +
+                        " milliseconds.");
+                Message msg = Message.obtain(mHandler, mSensorRestart);
+                msg.setAsynchronous(true);
+                mHandler.sendMessageDelayed(msg, ORIENTATION_MEASUREMENT_INTERVAL_MILLIS);
+            }
+        }
+        return status;
+    }
+
+    /*
+     * Updates mStatus to the current AnyMotion status.
+     */
+    public int getStationaryStatus() {
+        if ((mPreviousGravityVector == null) || (mCurrentGravityVector == null)) {
+            return RESULT_UNKNOWN;
+        }
+        Vector3 previousGravityVectorNormalized = mPreviousGravityVector.normalized();
+        Vector3 currentGravityVectorNormalized = mCurrentGravityVector.normalized();
+        float angle = previousGravityVectorNormalized.angleBetween(currentGravityVectorNormalized);
+        if (DEBUG) Slog.d(TAG, "getStationaryStatus: angle = " + angle);
+        if ((angle < THRESHOLD_ANGLE) && (mRunningStats.getEnergy() < THRESHOLD_ENERGY)) {
+            return RESULT_STATIONARY;
+        } else if (Float.isNaN(angle)) {
+          /**
+           * Floating point rounding errors have caused the angle calcuation's dot product to 
+           * exceed 1.0. In such case, we report RESULT_MOVED to prevent devices from rapidly
+           * retrying this measurement.
+           */
+            return RESULT_MOVED;
+        }
+        long diffTime = mCurrentGravityVector.timeMillisSinceBoot -
+                mPreviousGravityVector.timeMillisSinceBoot;
+        if (diffTime > STALE_MEASUREMENT_TIMEOUT_MILLIS) {
+            if (DEBUG) Slog.d(TAG, "getStationaryStatus: mPreviousGravityVector is too stale at " +
+                    diffTime + " ms ago. Returning RESULT_UNKNOWN.");
+            return RESULT_UNKNOWN;
+        }
+        return RESULT_MOVED;
+    }
+
+    private final SensorEventListener mListener = new SensorEventListener() {
+        @Override
+        public void onSensorChanged(SensorEvent event) {
+            int status = RESULT_UNKNOWN;
+            synchronized (mLock) {
+                Vector3 accelDatum = new Vector3(SystemClock.elapsedRealtime(), event.values[0],
+                        event.values[1], event.values[2]);
+                mRunningStats.accumulate(accelDatum);
+
+                // If we have enough samples, stop accelerometer data acquisition.
+                if (mRunningStats.getSampleCount() >= mNumSufficientSamples) {
+                    status = stopOrientationMeasurementLocked();
+                }
+            }
+            if (status != RESULT_UNKNOWN) {
+                mCallback.onAnyMotionResult(status);
+            }
+        }
+
+        @Override
+        public void onAccuracyChanged(Sensor sensor, int accuracy) {
+        }
+    };
+
+    private final Runnable mSensorRestart = new Runnable() {
+        @Override
+        public void run() {
+            synchronized (mLock) {
+                startOrientationMeasurement();
+            }
+        }
+    };
+
+    private final Runnable mMeasurementTimeout = new Runnable() {
+      @Override
+      public void run() {
+          int status = RESULT_UNKNOWN;
+          synchronized (mLock) {
+              if (DEBUG) Slog.i(TAG, "mMeasurementTimeout. Failed to collect sufficient accel " +
+                      "data within " + ACCELEROMETER_DATA_TIMEOUT_MILLIS + " ms. Stopping " +
+                      "orientation measurement.");
+              status = stopOrientationMeasurementLocked();
+          }
+          if (status != RESULT_UNKNOWN) {
+              mCallback.onAnyMotionResult(status);
+          }
+      }
+  };
+
+    /**
+     * A timestamped three dimensional vector and some vector operations.
+     */
+    private static class Vector3 {
+        public long timeMillisSinceBoot;
+        public float x;
+        public float y;
+        public float z;
+
+        public Vector3(long timeMillisSinceBoot, float x, float y, float z) {
+            this.timeMillisSinceBoot = timeMillisSinceBoot;
+            this.x = x;
+            this.y = y;
+            this.z = z;
+        }
+
+        private float norm() {
+            return (float) Math.sqrt(dotProduct(this));
+        }
+
+        private Vector3 normalized() {
+            float mag = norm();
+            return new Vector3(timeMillisSinceBoot, x / mag, y / mag, z / mag);
+        }
+
+        /**
+         * Returns the angle between this 3D vector and another given 3D vector.
+         * Assumes both have already been normalized.
+         *
+         * @param other The other Vector3 vector.
+         * @return angle between this vector and the other given one.
+         */
+        public float angleBetween(Vector3 other) {
+            double degrees = Math.toDegrees(Math.acos(this.dotProduct(other)));
+            float returnValue = (float) degrees;
+            Slog.d(TAG, "angleBetween: this = " + this.toString() +
+                    ", other = " + other.toString());
+            Slog.d(TAG, "    degrees = " + degrees + ", returnValue = " + returnValue);
+            return returnValue;
+        }
+
+        @Override
+        public String toString() {
+            String msg = "";
+            msg += "timeMillisSinceBoot=" + timeMillisSinceBoot;
+            msg += " | x=" + x;
+            msg += ", y=" + y;
+            msg += ", z=" + z;
+            return msg;
+        }
+
+        public float dotProduct(Vector3 v) {
+            return x * v.x + y * v.y + z * v.z;
+        }
+
+        public Vector3 times(float val) {
+            return new Vector3(timeMillisSinceBoot, x * val, y * val, z * val);
+        }
+
+        public Vector3 plus(Vector3 v) {
+            return new Vector3(v.timeMillisSinceBoot, x + v.x, y + v.y, z + v.z);
+        }
+
+        public Vector3 minus(Vector3 v) {
+            return new Vector3(v.timeMillisSinceBoot, x - v.x, y - v.y, z - v.z);
+        }
+    }
+
+    /**
+     * Maintains running statistics on the signal revelant to AnyMotion detection, including:
+     * <ul>
+     *   <li>running average.
+     *   <li>running sum-of-squared-errors as the energy of the signal derivative.
+     * <ul>
+     */
+    private static class RunningSignalStats {
+        Vector3 previousVector;
+        Vector3 currentVector;
+        Vector3 runningSum;
+        float energy;
+        int sampleCount;
+
+        public RunningSignalStats() {
+            reset();
+        }
+
+        public void reset() {
+            previousVector = null;
+            currentVector = null;
+            runningSum = new Vector3(0, 0, 0, 0);
+            energy = 0;
+            sampleCount = 0;
+        }
+
+        /**
+         * Apply a 3D vector v as the next element in the running SSE.
+         */
+        public void accumulate(Vector3 v) {
+            if (v == null) {
+                if (DEBUG) Slog.i(TAG, "Cannot accumulate a null vector.");
+                return;
+            }
+            sampleCount++;
+            runningSum = runningSum.plus(v);
+            previousVector = currentVector;
+            currentVector = v;
+            if (previousVector != null) {
+                Vector3 dv = currentVector.minus(previousVector);
+                float incrementalEnergy = dv.x * dv.x + dv.y * dv.y + dv.z * dv.z;
+                energy += incrementalEnergy;
+                if (DEBUG) Slog.i(TAG, "Accumulated vector " + currentVector.toString() +
+                        ", runningSum = " + runningSum.toString() +
+                        ", incrementalEnergy = " + incrementalEnergy +
+                        ", energy = " + energy);
+            }
+        }
+
+        public Vector3 getRunningAverage() {
+            if (sampleCount > 0) {
+              return runningSum.times((float)(1.0f / sampleCount));
+            }
+            return null;
+        }
+
+        public float getEnergy() {
+            return energy;
+        }
+
+        public int getSampleCount() {
+            return sampleCount;
+        }
+
+        @Override
+        public String toString() {
+            String msg = "";
+            String currentVectorString = (currentVector == null) ?
+                "null" : currentVector.toString();
+            String previousVectorString = (previousVector == null) ?
+                "null" : previousVector.toString();
+            msg += "previousVector = " + previousVectorString;
+            msg += ", currentVector = " + currentVectorString;
+            msg += ", sampleCount = " + sampleCount;
+            msg += ", energy = " + energy;
+            return msg;
+        }
+    }
+}

services/core/java/com/android/server/DeviceIdleController.java

@@ -85,10 +85,12 @@ import java.util.Arrays;
 /**
  * Keeps track of device idleness and drives low power mode based on that.
  */
-public class DeviceIdleController extends SystemService {
+public class DeviceIdleController extends SystemService
+        implements AnyMotionDetector.DeviceIdleCallback {
     private static final String TAG = "DeviceIdleController";
 
     private static final boolean DEBUG = false;
+
     private static final boolean COMPRESS_TIME = false;
 
     public static final String SERVICE_NAME = "deviceidle";
@@ -96,6 +98,9 @@ public class DeviceIdleController extends SystemService {
     private static final String ACTION_STEP_IDLE_STATE =
             "com.android.server.device_idle.STEP_IDLE_STATE";
 
+    private static final String ACTION_ENTER_INACTIVE_STATE =
+        "com.android.server.device_idle.ENTER_INACTIVE_STATE";
+
     // TODO: These need to be moved to system settings.
 
     /**
@@ -104,26 +109,40 @@ public class DeviceIdleController extends SystemService {
      * immediately after going inactive just because we don't want to be continually running
      * the significant motion sensor whenever the screen is off.
      */
+
     private static final long DEFAULT_INACTIVE_TIMEOUT = !COMPRESS_TIME ? 30*60*1000L
             : 3 * 60 * 1000L;
+
+    /**
+     * If we don't receive a callback from AnyMotion in this amount of time, we will change from
+     * STATE_SENSING to STATE_INACTIVE, and any AnyMotion callbacks while not in STATE_SENSING will
+     * be ignored.
+     */
+    private static final long DEFAULT_SENSING_TIMEOUT = !DEBUG ? 5 * 60 * 1000L : 60 * 1000L;
+
     /**
      * This is the time, after seeing motion, that we wait after becoming inactive from
      * that until we start looking for motion again.
      */
     private static final long DEFAULT_MOTION_INACTIVE_TIMEOUT = !COMPRESS_TIME ? 10*60*1000L
             : 60 * 1000L;
+
     /**
      * This is the time, after the inactive timeout elapses, that we will wait looking
      * for significant motion until we truly consider the device to be idle.
      */
+
     private static final long DEFAULT_IDLE_AFTER_INACTIVE_TIMEOUT = !COMPRESS_TIME ? 30*60*1000L
             : 3 * 60 * 1000L;
+
     /**
      * This is the initial time, after being idle, that we will allow ourself to be back
      * in the IDLE_PENDING state allowing the system to run normally until we return to idle.
      */
+
     private static final long DEFAULT_IDLE_PENDING_TIMEOUT = !COMPRESS_TIME ? 5*60*1000L
             : 30 * 1000L;
+
     /**
      * Maximum pending idle timeout (time spent running) we will be allowed to use.
      */
@@ -138,8 +157,10 @@ public class DeviceIdleController extends SystemService {
      * This is the initial time that we want to sit in the idle state before waking up
      * again to return to pending idle and allowing normal work to run.
      */
+
     private static final long DEFAULT_IDLE_TIMEOUT = !COMPRESS_TIME ? 60*60*1000L
             : 6 * 60 * 1000L;
+
     /**
      * Maximum idle duration we will be allowed to use.
      */
@@ -168,9 +189,11 @@ public class DeviceIdleController extends SystemService {
     private DisplayManager mDisplayManager;
     private SensorManager mSensorManager;
     private Sensor mSigMotionSensor;
+    private PendingIntent mSensingAlarmIntent;
     private PendingIntent mAlarmIntent;
     private Intent mIdleIntent;
     private Display mCurDisplay;
+    private AnyMotionDetector mAnyMotionDetector;
     private boolean mIdleDisabled;
     private boolean mScreenOn;
     private boolean mCharging;
@@ -182,15 +205,18 @@ public class DeviceIdleController extends SystemService {
     private static final int STATE_INACTIVE = 1;
     /** Device is past the initial inactive period, and waiting for the next idle period. */
     private static final int STATE_IDLE_PENDING = 2;
+    /** Device is currently sensing motion. */
+    private static final int STATE_SENSING = 3;
     /** Device is in the idle state, trying to stay asleep as much as possible. */
-    private static final int STATE_IDLE = 3;
+    private static final int STATE_IDLE = 4;
     /** Device is in the idle state, but temporarily out of idle to do regular maintenance. */
-    private static final int STATE_IDLE_MAINTENANCE = 4;
+    private static final int STATE_IDLE_MAINTENANCE = 5;
     private static String stateToString(int state) {
         switch (state) {
             case STATE_ACTIVE: return "ACTIVE";
             case STATE_INACTIVE: return "INACTIVE";
             case STATE_IDLE_PENDING: return "IDLE_PENDING";
+            case STATE_SENSING: return "SENSING";
             case STATE_IDLE: return "IDLE";
             case STATE_IDLE_MAINTENANCE: return "IDLE_MAINTENANCE";
             default: return Integer.toString(state);
@@ -247,6 +273,10 @@ public class DeviceIdleController extends SystemService {
                 synchronized (DeviceIdleController.this) {
                     stepIdleStateLocked();
                 }
+            } else if (ACTION_ENTER_INACTIVE_STATE.equals(intent.getAction())) {
+                synchronized (DeviceIdleController.this) {
+                    enterInactiveStateLocked();
+                }
             }
         }
     };
@@ -276,6 +306,24 @@ public class DeviceIdleController extends SystemService {
         }
     };
 
+    @Override
+    public void onAnyMotionResult(int result) {
+        if (DEBUG) Slog.d(TAG, "onAnyMotionResult(" + result + ")");
+        if (mState == STATE_SENSING) {
+            if (result == AnyMotionDetector.RESULT_STATIONARY) {
+                if (DEBUG) Slog.d(TAG, "RESULT_STATIONARY received.");
+                synchronized (this) {
+                    stepIdleStateLocked();
+                }
+            } else if (result == AnyMotionDetector.RESULT_MOVED) {
+                if (DEBUG) Slog.d(TAG, "RESULT_MOVED received.");
+                synchronized (this) {
+                    enterInactiveStateLocked();
+                }
+            }
+        }
+    }
+
     static final int MSG_WRITE_CONFIG = 1;
     static final int MSG_REPORT_IDLE_ON = 2;
     static final int MSG_REPORT_IDLE_OFF = 3;
@@ -288,6 +336,7 @@ public class DeviceIdleController extends SystemService {
         }
 
         @Override public void handleMessage(Message msg) {
+            if (DEBUG) Slog.d(TAG, "handleMessage(" + msg.what + ")");
             switch (msg.what) {
                 case MSG_WRITE_CONFIG: {
                     handleWriteConfigFile();
@@ -452,12 +501,21 @@ public class DeviceIdleController extends SystemService {
                         Context.DISPLAY_SERVICE);
                 mSensorManager = (SensorManager) getContext().getSystemService(Context.SENSOR_SERVICE);
                 mSigMotionSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_SIGNIFICANT_MOTION);
+                mAnyMotionDetector = new AnyMotionDetector(
+                        mAlarmManager,
+                        (PowerManager) getContext().getSystemService(Context.POWER_SERVICE),
+                        mHandler, mSensorManager, this);
 
                 Intent intent = new Intent(ACTION_STEP_IDLE_STATE)
                         .setPackage("android")
                         .setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
                 mAlarmIntent = PendingIntent.getBroadcast(getContext(), 0, intent, 0);
 
+                Intent intentSensing = new Intent(ACTION_STEP_IDLE_STATE)
+                        .setPackage("android")
+                        .setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
+                mSensingAlarmIntent = PendingIntent.getBroadcast(getContext(), 0, intentSensing, 0);
+
                 mIdleIntent = new Intent(PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED);
                 mIdleIntent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
 
@@ -613,6 +671,7 @@ public class DeviceIdleController extends SystemService {
         // because if there is anything shown we are going to be updating it at some
         // frequency so can't be allowed to go into deep sleeps.
         boolean screenOn = mCurDisplay.getState() != Display.STATE_OFF;;
+        if (DEBUG) Slog.d(TAG, "updateDisplayLocked: screenOn=" + screenOn);
         if (!screenOn && mScreenOn) {
             mScreenOn = false;
             becomeInactiveIfAppropriateLocked();
@@ -623,6 +682,7 @@ public class DeviceIdleController extends SystemService {
     }
 
     void updateChargingLocked(boolean charging) {
+        if (DEBUG) Slog.i(TAG, "updateChargingLocked: charging=" + charging);
         if (!charging && mCharging) {
             mCharging = false;
             becomeInactiveIfAppropriateLocked();
@@ -639,6 +699,7 @@ public class DeviceIdleController extends SystemService {
     }
 
     void becomeActiveLocked(String reason) {
+        if (DEBUG) Slog.i(TAG, "becomeActiveLocked, reason = " + reason);
         if (mState != STATE_ACTIVE) {
             EventLogTags.writeDeviceIdle(STATE_ACTIVE, reason);
             scheduleReportActiveLocked(false);
@@ -652,10 +713,12 @@ public class DeviceIdleController extends SystemService {
     }
 
     void becomeInactiveIfAppropriateLocked() {
+        if (DEBUG) Slog.d(TAG, "becomeInactiveIfAppropriateLocked()");
         if (!mScreenOn && !mCharging && !mIdleDisabled && mState == STATE_ACTIVE) {
             // Screen has turned off; we are now going to become inactive and start
             // waiting to see if we will ultimately go idle.
             mState = STATE_INACTIVE;
+            if (DEBUG) Slog.d(TAG, "Moved from STATE_ACTIVE to STATE_INACTIVE");
             mNextIdlePendingDelay = 0;
             mNextIdleDelay = 0;
             scheduleAlarmLocked(mInactiveTimeout, false);
@@ -663,7 +726,17 @@ public class DeviceIdleController extends SystemService {
         }
     }
 
+    /**
+     * This is called when we've failed to receive a callback from AnyMotionDetector
+     * within the DEFAULT_SENSING_TIMEOUT, to return to STATE_INACTIVE.
+     */
+    void enterInactiveStateLocked() {
+        mInactiveTimeout = DEFAULT_INACTIVE_TIMEOUT;
+        becomeInactiveIfAppropriateLocked();
+    }
+
     void stepIdleStateLocked() {
+        if (DEBUG) Slog.d(TAG, "stepIdleStateLocked: mState=" + mState);
         EventLogTags.writeDeviceIdleStep();
 
         final long now = SystemClock.elapsedRealtime();
@@ -685,26 +758,34 @@ public class DeviceIdleController extends SystemService {
                 mNextIdlePendingDelay = DEFAULT_IDLE_PENDING_TIMEOUT;
                 mNextIdleDelay = DEFAULT_IDLE_TIMEOUT;
                 mState = STATE_IDLE_PENDING;
+                if (DEBUG) Slog.d(TAG, "Moved from STATE_INACTIVE to STATE_IDLE_PENDING.");
                 EventLogTags.writeDeviceIdle(mState, "step");
                 break;
             case STATE_IDLE_PENDING:
+                mState = STATE_SENSING;
+                if (DEBUG) Slog.d(TAG, "Moved from STATE_IDLE_PENDING to STATE_SENSING.");
+                scheduleSensingAlarmLocked(DEFAULT_SENSING_TIMEOUT);
+                mAnyMotionDetector.checkForAnyMotion();
+                break;
+            case STATE_SENSING:
+                cancelSensingAlarmLocked();
             case STATE_IDLE_MAINTENANCE:
-                // We have been waiting to become idle, and now it is time!  This is the
-                // only case where we want to use a wakeup alarm, because we do want to
-                // drag the device out of its sleep state in this case to do the next
-                // scheduled work.
                 scheduleAlarmLocked(mNextIdleDelay, true);
-                mNextIdleDelay = (long)(mNextIdleDelay*DEFAULT_IDLE_FACTOR);
+                if (DEBUG) Slog.d(TAG, "Moved to STATE_IDLE. Next alarm in " + mNextIdleDelay +
+                        " ms.");
+                mNextIdleDelay = (long)(mNextIdleDelay * DEFAULT_IDLE_FACTOR);
+                if (DEBUG) Slog.d(TAG, "Setting mNextIdleDelay = " + mNextIdleDelay);
                 if (mNextIdleDelay > DEFAULT_MAX_IDLE_TIMEOUT) {
                     mNextIdleDelay = DEFAULT_MAX_IDLE_TIMEOUT;
                 }
                 mState = STATE_IDLE;
-                EventLogTags.writeDeviceIdle(mState, "step");
                 mHandler.sendEmptyMessage(MSG_REPORT_IDLE_ON);
                 break;
             case STATE_IDLE:
                 // We have been idling long enough, now it is time to do some work.
                 scheduleAlarmLocked(mNextIdlePendingDelay, false);
+                if (DEBUG) Slog.d(TAG, "Moved from STATE_IDLE to STATE_IDLE_MAINTENANCE. " +
+                        "Next alarm in " + mNextIdlePendingDelay + " ms.");
                 mNextIdlePendingDelay = (long)(mNextIdlePendingDelay*DEFAULT_IDLE_PENDING_FACTOR);
                 if (mNextIdlePendingDelay > DEFAULT_MAX_IDLE_PENDING_TIMEOUT) {
                     mNextIdlePendingDelay = DEFAULT_MAX_IDLE_PENDING_TIMEOUT;
@@ -717,6 +798,7 @@ public class DeviceIdleController extends SystemService {
     }
 
     void significantMotionLocked() {
+        if (DEBUG) Slog.d(TAG, "significantMotionLocked()");
         // When the sensor goes off, its trigger is automatically removed.
         mSigMotionActive = false;
         // The device is not yet active, so we want to go back to the pending idle
@@ -732,6 +814,7 @@ public class DeviceIdleController extends SystemService {
     }
 
     void startMonitoringSignificantMotion() {
+        if (DEBUG) Slog.d(TAG, "startMonitoringSignificantMotion()");
         if (mSigMotionSensor != null && !mSigMotionActive) {
             mSensorManager.requestTriggerSensor(mSigMotionListener, mSigMotionSensor);
             mSigMotionActive = true;
@@ -739,6 +822,7 @@ public class DeviceIdleController extends SystemService {
     }
 
     void stopMonitoringSignificantMotion() {
+        if (DEBUG) Slog.d(TAG, "stopMonitoringSignificantMotion()");
         if (mSigMotionActive) {
             mSensorManager.cancelTriggerSensor(mSigMotionListener, mSigMotionSensor);
             mSigMotionActive = false;
@@ -752,7 +836,13 @@ public class DeviceIdleController extends SystemService {
         }
     }
 
+    void cancelSensingAlarmLocked() {
+        if (DEBUG) Slog.d(TAG, "cancelSensingAlarmLocked()");
+        mAlarmManager.cancel(mSensingAlarmIntent);
+    }
+
     void scheduleAlarmLocked(long delay, boolean idleUntil) {
+        if (DEBUG) Slog.d(TAG, "scheduleAlarmLocked(" + delay + ", " + idleUntil + ")");
         if (mSigMotionSensor == null) {
             // If there is no significant motion sensor on this device, then we won't schedule
             // alarms, because we can't determine if the device is not moving.  This effectively
@@ -770,6 +860,13 @@ public class DeviceIdleController extends SystemService {
         }
     }
 
+    void scheduleSensingAlarmLocked(long delay) {
+      if (DEBUG) Slog.d(TAG, "scheduleSensingAlarmLocked(" + delay + ")");
+      mNextAlarmTime = SystemClock.elapsedRealtime() + delay;
+      mAlarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,
+          mNextAlarmTime, mSensingAlarmIntent);
+    }
+
     private void updateWhitelistAppIdsLocked() {
         mPowerSaveWhitelistAppIds.clear();
         for (int i=0; i<mPowerSaveWhitelistApps.size(); i++) {