Merge "Improve heuristics for detecting wireless chargers." into jb-mr1.1-dev

3 files changed, 355 insertions, 40 deletions

diff --git a/services/java/com/android/server/power/DisplayPowerController.java b/services/java/com/android/server/power/DisplayPowerController.java
index 724e126..b5010f2 100644
--- a/services/java/com/android/server/power/DisplayPowerController.java
+++ b/services/java/com/android/server/power/DisplayPowerController.java
@@ -344,7 +344,7 @@ final class DisplayPowerController {
      * Creates the display power controller.
      */
     public DisplayPowerController(Looper looper, Context context, Notifier notifier,
-            LightsService lights, TwilightService twilight,
+            LightsService lights, TwilightService twilight, SensorManager sensorManager,
             DisplayManagerService displayManager,
             DisplayBlanker displayBlanker,
             Callbacks callbacks, Handler callbackHandler) {
@@ -356,7 +356,7 @@ final class DisplayPowerController {
 
         mLights = lights;
         mTwilight = twilight;
-        mSensorManager = new SystemSensorManager(mHandler.getLooper());
+        mSensorManager = sensorManager;
         mDisplayManager = displayManager;
 
         final Resources resources = context.getResources();
diff --git a/services/java/com/android/server/power/PowerManagerService.java b/services/java/com/android/server/power/PowerManagerService.java
index 5a5d910..546f22e 100644
--- a/services/java/com/android/server/power/PowerManagerService.java
+++ b/services/java/com/android/server/power/PowerManagerService.java
@@ -35,6 +35,8 @@ import android.content.IntentFilter;
 import android.content.pm.PackageManager;
 import android.content.res.Resources;
 import android.database.ContentObserver;
+import android.hardware.SensorManager;
+import android.hardware.SystemSensorManager;
 import android.net.Uri;
 import android.os.BatteryManager;
 import android.os.Binder;
@@ -153,11 +155,6 @@ public final class PowerManagerService extends IPowerManager.Stub
     // Otherwise the user won't get much screen on time before dimming occurs.
     private static final float MAXIMUM_SCREEN_DIM_RATIO = 0.2f;
 
-    // Upper bound on the battery charge percentage in order to consider turning
-    // the screen on when the device starts charging wirelessly.
-    // See point of use for more details.
-    private static final int WIRELESS_CHARGER_TURN_ON_BATTERY_LEVEL_LIMIT = 95;
-
     // The name of the boot animation service in init.rc.
     private static final String BOOT_ANIMATION_SERVICE = "bootanim";
 
@@ -179,6 +176,7 @@ public final class PowerManagerService extends IPowerManager.Stub
     private WindowManagerPolicy mPolicy;
     private Notifier mNotifier;
     private DisplayPowerController mDisplayPowerController;
+    private WirelessChargerDetector mWirelessChargerDetector;
     private SettingsObserver mSettingsObserver;
     private DreamManagerService mDreamManager;
     private LightsService.Light mAttentionLight;
@@ -423,6 +421,8 @@ public final class PowerManagerService extends IPowerManager.Stub
             mScreenBrightnessSettingMaximum = pm.getMaximumScreenBrightnessSetting();
             mScreenBrightnessSettingDefault = pm.getDefaultScreenBrightnessSetting();
 
+            SensorManager sensorManager = new SystemSensorManager(mHandler.getLooper());
+
             // The notifier runs on the system server's main looper so as not to interfere
             // with the animations and other critical functions of the power manager.
             mNotifier = new Notifier(Looper.getMainLooper(), mContext, mBatteryStats,
@@ -430,11 +430,14 @@ public final class PowerManagerService extends IPowerManager.Stub
                     mScreenOnBlocker, mPolicy);
 
             // The display power controller runs on the power manager service's
-            // own handler thread.
+            // own handler thread to ensure timely operation.
             mDisplayPowerController = new DisplayPowerController(mHandler.getLooper(),
-                    mContext, mNotifier, mLightsService, twilight, mDisplayManagerService,
-                    mDisplayBlanker, mDisplayPowerControllerCallbacks, mHandler);
+                    mContext, mNotifier, mLightsService, twilight, sensorManager,
+                    mDisplayManagerService, mDisplayBlanker,
+                    mDisplayPowerControllerCallbacks, mHandler);
 
+            mWirelessChargerDetector = new WirelessChargerDetector(sensorManager,
+                    createSuspendBlockerLocked("PowerManagerService.WirelessChargerDetector"));
             mSettingsObserver = new SettingsObserver(mHandler);
             mAttentionLight = mLightsService.getLight(LightsService.LIGHT_ID_ATTENTION);
 
@@ -1139,65 +1142,51 @@ public final class PowerManagerService extends IPowerManager.Stub
             if (wasPowered != mIsPowered || oldPlugType != mPlugType) {
                 mDirty |= DIRTY_IS_POWERED;
 
+                // Update wireless dock detection state.
+                final boolean dockedOnWirelessCharger = mWirelessChargerDetector.update(
+                        mIsPowered, mPlugType, mBatteryLevel);
+
                 // Treat plugging and unplugging the devices as a user activity.
                 // Users find it disconcerting when they plug or unplug the device
                 // and it shuts off right away.
                 // Some devices also wake the device when plugged or unplugged because
                 // they don't have a charging LED.
                 final long now = SystemClock.uptimeMillis();
-                if (shouldWakeUpWhenPluggedOrUnpluggedLocked(wasPowered, oldPlugType)) {
+                if (shouldWakeUpWhenPluggedOrUnpluggedLocked(wasPowered, oldPlugType,
+                        dockedOnWirelessCharger)) {
                     wakeUpNoUpdateLocked(now);
                 }
                 userActivityNoUpdateLocked(
                         now, PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, Process.SYSTEM_UID);
 
                 // Tell the notifier whether wireless charging has started so that
-                // it can provide feedback to the user.  Refer to
-                // shouldWakeUpWhenPluggedOrUnpluggedLocked for justification of the
-                // heuristics used here.
-                if (!wasPowered && mIsPowered
-                        && mPlugType == BatteryManager.BATTERY_PLUGGED_WIRELESS
-                        && mBatteryLevel < WIRELESS_CHARGER_TURN_ON_BATTERY_LEVEL_LIMIT) {
+                // it can provide feedback to the user.
+                if (dockedOnWirelessCharger) {
                     mNotifier.onWirelessChargingStarted();
                 }
             }
         }
     }
 
-    private boolean shouldWakeUpWhenPluggedOrUnpluggedLocked(boolean wasPowered, int oldPlugType) {
+    private boolean shouldWakeUpWhenPluggedOrUnpluggedLocked(
+            boolean wasPowered, int oldPlugType, boolean dockedOnWirelessCharger) {
         // Don't wake when powered unless configured to do so.
         if (!mWakeUpWhenPluggedOrUnpluggedConfig) {
             return false;
         }
 
-        // FIXME: Need more accurate detection of wireless chargers.
-        //
-        // We are unable to accurately detect whether the device is resting on the
-        // charger unless it is actually receiving power.  This causes us some grief
-        // because the device might not appear to be plugged into the wireless charger
-        // unless it actually charging.
-        //
-        // To avoid spuriously waking the screen, we apply a special policy to
-        // wireless chargers.
-        //
-        // 1. Don't wake the device when unplugged from wireless charger because
-        //    it might be that the device is still resting on the wireless charger
-        //    but is not receiving power anymore because the battery is full.
-        //
-        // 2. Don't wake the device when plugged into a wireless charger if the
-        //    battery already appears to be mostly full.  This situation may indicate
-        //    that the device was resting on the charger the whole time and simply
-        //    wasn't receiving power because the battery was full.  We can't tell
-        //    whether the device was just placed on the charger or whether it has
-        //    been there for half of the night slowly discharging until it hit
-        //    the point where it needed to start charging again.
+        // Don't wake when undocked from wireless charger.
+        // See WirelessChargerDetector for justification.
         if (wasPowered && !mIsPowered
                 && oldPlugType == BatteryManager.BATTERY_PLUGGED_WIRELESS) {
             return false;
         }
+
+        // Don't wake when docked on wireless charger unless we are certain of it.
+        // See WirelessChargerDetector for justification.
         if (!wasPowered && mIsPowered
                 && mPlugType == BatteryManager.BATTERY_PLUGGED_WIRELESS
-                && mBatteryLevel >= WIRELESS_CHARGER_TURN_ON_BATTERY_LEVEL_LIMIT) {
+                && !dockedOnWirelessCharger) {
             return false;
         }
 
@@ -2183,6 +2172,7 @@ public final class PowerManagerService extends IPowerManager.Stub
         pw.println("POWER MANAGER (dumpsys power)\n");
 
         final DisplayPowerController dpc;
+        final WirelessChargerDetector wcd;
         synchronized (mLock) {
             pw.println("Power Manager State:");
             pw.println("  mDirty=0x" + Integer.toHexString(mDirty));
@@ -2264,11 +2254,16 @@ public final class PowerManagerService extends IPowerManager.Stub
             pw.println("Display Blanker: " + mDisplayBlanker);
 
             dpc = mDisplayPowerController;
+            wcd = mWirelessChargerDetector;
         }
 
         if (dpc != null) {
             dpc.dump(pw);
         }
+
+        if (wcd != null) {
+            wcd.dump(pw);
+        }
     }
 
     private SuspendBlocker createSuspendBlockerLocked(String name) {
diff --git a/services/java/com/android/server/power/WirelessChargerDetector.java b/services/java/com/android/server/power/WirelessChargerDetector.java
new file mode 100644
index 0000000..ac6dc3e
--- /dev/null
+++ b/services/java/com/android/server/power/WirelessChargerDetector.java
@@ -0,0 +1,320 @@
+/*
+ * Copyright (C) 2013 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.power;
+
+import android.hardware.Sensor;
+import android.hardware.SensorEvent;
+import android.hardware.SensorEventListener;
+import android.hardware.SensorManager;
+import android.os.BatteryManager;
+import android.util.Slog;
+
+import java.io.PrintWriter;
+
+/**
+ * Implements heuristics to detect docking or undocking from a wireless charger.
+ * <p>
+ * Some devices have wireless charging circuits that are unable to detect when the
+ * device is resting on a wireless charger except when the device is actually
+ * receiving power from the charger.  The device may stop receiving power
+ * if the battery is already nearly full or if it is too hot.  As a result, we cannot
+ * always rely on the battery service wireless plug signal to accurately indicate
+ * whether the device has been docked or undocked from a wireless charger.
+ * </p><p>
+ * This is a problem because the power manager typically wakes up the screen and
+ * plays a tone when the device is docked in a wireless charger.  It is important
+ * for the system to suppress spurious docking and undocking signals because they
+ * can be intrusive for the user (especially if they cause a tone to be played
+ * late at night for no apparent reason).
+ * </p><p>
+ * To avoid spurious signals, we apply some special policies to wireless chargers.
+ * </p><p>
+ * 1. Don't wake the device when undocked from the wireless charger because
+ * it might be that the device is still resting on the wireless charger
+ * but is not receiving power anymore because the battery is full.
+ * Ideally we would wake the device if we could be certain that the user had
+ * picked it up from the wireless charger but due to hardware limitations we
+ * must be more conservative.
+ * </p><p>
+ * 2. Don't wake the device when docked on a wireless charger if the
+ * battery already appears to be mostly full.  This situation may indicate
+ * that the device was resting on the charger the whole time and simply
+ * wasn't receiving power because the battery was already full.  We can't tell
+ * whether the device was just placed on the charger or whether it has
+ * been there for half of the night slowly discharging until it reached
+ * the point where it needed to start charging again.  So we suppress docking
+ * signals that occur when the battery level is above a given threshold.
+ * </p><p>
+ * 3. Don't wake the device when docked on a wireless charger if it does
+ * not appear to have moved since it was last undocked because it may
+ * be that the prior undocking signal was spurious.  We use the gravity
+ * sensor to detect this case.
+ * </p>
+ */
+final class WirelessChargerDetector {
+    private static final String TAG = "WirelessChargerDetector";
+    private static final boolean DEBUG = false;
+
+    // Number of nanoseconds per millisecond.
+    private static final long NANOS_PER_MS = 1000000;
+
+    // The minimum amount of time to spend watching the sensor before making
+    // a determination of whether movement occurred.
+    private static final long SETTLE_TIME_NANOS = 500 * NANOS_PER_MS;
+
+    // The minimum number of samples that must be collected.
+    private static final int MIN_SAMPLES = 3;
+
+    // Upper bound on the battery charge percentage in order to consider turning
+    // the screen on when the device starts charging wirelessly.
+    private static final int WIRELESS_CHARGER_TURN_ON_BATTERY_LEVEL_LIMIT = 95;
+
+    // To detect movement, we compute the angle between the gravity vector
+    // at rest and the current gravity vector.  This field specifies the
+    // cosine of the maximum angle variance that we tolerate while at rest.
+    private static final double MOVEMENT_ANGLE_COS_THRESHOLD = Math.cos(5 * Math.PI / 180);
+
+    // Sanity thresholds for the gravity vector.
+    private static final double MIN_GRAVITY = SensorManager.GRAVITY_EARTH - 1.0f;
+    private static final double MAX_GRAVITY = SensorManager.GRAVITY_EARTH + 1.0f;
+
+    private final Object mLock = new Object();
+
+    private final SensorManager mSensorManager;
+    private final SuspendBlocker mSuspendBlocker;
+
+    // The gravity sensor, or null if none.
+    private Sensor mGravitySensor;
+
+    // Previously observed wireless power state.
+    private boolean mPoweredWirelessly;
+
+    // True if the device is thought to be at rest on a wireless charger.
+    private boolean mAtRest;
+
+    // The gravity vector most recently observed while at rest.
+    private float mRestX, mRestY, mRestZ;
+
+    /* These properties are only meaningful while detection is in progress. */
+
+    // True if detection is in progress.
+    // The suspend blocker is held while this is the case.
+    private boolean mDetectionInProgress;
+
+    // True if the rest position should be updated if at rest.
+    // Otherwise, the current rest position is simply checked and cleared if movement
+    // is detected but no new rest position is stored.
+    private boolean mMustUpdateRestPosition;
+
+    // The total number of samples collected.
+    private int mTotalSamples;
+
+    // The number of samples collected that showed evidence of not being at rest.
+    private int mMovingSamples;
+
+    // The time and value of the first sample that was collected.
+    private long mFirstSampleTime;
+    private float mFirstSampleX, mFirstSampleY, mFirstSampleZ;
+
+    public WirelessChargerDetector(SensorManager sensorManager,
+            SuspendBlocker suspendBlocker) {
+        mSensorManager = sensorManager;
+        mSuspendBlocker = suspendBlocker;
+
+        mGravitySensor = sensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY);
+    }
+
+    public void dump(PrintWriter pw) {
+        synchronized (mLock) {
+            pw.println();
+            pw.println("Wireless Charger Detector State:");
+            pw.println("  mGravitySensor=" + mGravitySensor);
+            pw.println("  mPoweredWirelessly=" + mPoweredWirelessly);
+            pw.println("  mAtRest=" + mAtRest);
+            pw.println("  mRestX=" + mRestX + ", mRestY=" + mRestY + ", mRestZ=" + mRestZ);
+            pw.println("  mDetectionInProgress=" + mDetectionInProgress);
+            pw.println("  mMustUpdateRestPosition=" + mMustUpdateRestPosition);
+            pw.println("  mTotalSamples=" + mTotalSamples);
+            pw.println("  mMovingSamples=" + mMovingSamples);
+            pw.println("  mFirstSampleTime=" + mFirstSampleTime);
+            pw.println("  mFirstSampleX=" + mFirstSampleX
+                    + ", mFirstSampleY=" + mFirstSampleY + ", mFirstSampleZ=" + mFirstSampleZ);
+        }
+    }
+
+    /**
+     * Updates the charging state and returns true if docking was detected.
+     *
+     * @param isPowered True if the device is powered.
+     * @param plugType The current plug type.
+     * @param batteryLevel The current battery level.
+     * @return True if the device is determined to have just been docked on a wireless
+     * charger, after suppressing spurious docking or undocking signals.
+     */
+    public boolean update(boolean isPowered, int plugType, int batteryLevel) {
+        synchronized (mLock) {
+            final boolean wasPoweredWirelessly = mPoweredWirelessly;
+
+            if (isPowered && plugType == BatteryManager.BATTERY_PLUGGED_WIRELESS) {
+                // The device is receiving power from the wireless charger.
+                // Update the rest position asynchronously.
+                mPoweredWirelessly = true;
+                mMustUpdateRestPosition = true;
+                startDetectionLocked();
+            } else {
+                // The device may or may not be on the wireless charger depending on whether
+                // the unplug signal that we received was spurious.
+                mPoweredWirelessly = false;
+                if (mAtRest) {
+                    if (plugType != 0 && plugType != BatteryManager.BATTERY_PLUGGED_WIRELESS) {
+                        // The device was plugged into a new non-wireless power source.
+                        // It's safe to assume that it is no longer on the wireless charger.
+                        mMustUpdateRestPosition = false;
+                        clearAtRestLocked();
+                    } else {
+                        // The device may still be on the wireless charger but we don't know.
+                        // Check whether the device has remained at rest on the charger
+                        // so that we will know to ignore the next wireless plug event
+                        // if needed.
+                        startDetectionLocked();
+                    }
+                }
+            }
+
+            // Report that the device has been docked only if the device just started
+            // receiving power wirelessly, has a high enough battery level that we
+            // can be assured that charging was not delayed due to the battery previously
+            // having been full, and the device is not known to already be at rest
+            // on the wireless charger from earlier.
+            return mPoweredWirelessly && !wasPoweredWirelessly
+                    && batteryLevel < WIRELESS_CHARGER_TURN_ON_BATTERY_LEVEL_LIMIT
+                    && !mAtRest;
+        }
+    }
+
+    private void startDetectionLocked() {
+        if (!mDetectionInProgress && mGravitySensor != null) {
+            if (mSensorManager.registerListener(mListener, mGravitySensor,
+                    SensorManager.SENSOR_DELAY_UI)) {
+                mSuspendBlocker.acquire();
+                mDetectionInProgress = true;
+                mTotalSamples = 0;
+                mMovingSamples = 0;
+            }
+        }
+    }
+
+    private void processSample(long timeNanos, float x, float y, float z) {
+        synchronized (mLock) {
+            if (!mDetectionInProgress) {
+                return;
+            }
+
+            mTotalSamples += 1;
+            if (mTotalSamples == 1) {
+                // Save information about the first sample collected.
+                mFirstSampleTime = timeNanos;
+                mFirstSampleX = x;
+                mFirstSampleY = y;
+                mFirstSampleZ = z;
+            } else {
+                // Determine whether movement has occurred relative to the first sample.
+                if (hasMoved(mFirstSampleX, mFirstSampleY, mFirstSampleZ, x, y, z)) {
+                    mMovingSamples += 1;
+                }
+            }
+
+            // Clear the at rest flag if movement has occurred relative to the rest sample.
+            if (mAtRest && hasMoved(mRestX, mRestY, mRestZ, x, y, z)) {
+                if (DEBUG) {
+                    Slog.d(TAG, "No longer at rest: "
+                            + "mRestX=" + mRestX + ", mRestY=" + mRestY + ", mRestZ=" + mRestZ
+                            + ", x=" + x + ", y=" + y + ", z=" + z);
+                }
+                clearAtRestLocked();
+            }
+
+            // Save the result when done.
+            if (timeNanos - mFirstSampleTime >= SETTLE_TIME_NANOS
+                    && mTotalSamples >= MIN_SAMPLES) {
+                mSensorManager.unregisterListener(mListener);
+                if (mMustUpdateRestPosition) {
+                    if (mMovingSamples == 0) {
+                        mAtRest = true;
+                        mRestX = x;
+                        mRestY = y;
+                        mRestZ = z;
+                    } else {
+                        clearAtRestLocked();
+                    }
+                    mMustUpdateRestPosition = false;
+                }
+                mDetectionInProgress = false;
+                mSuspendBlocker.release();
+
+                if (DEBUG) {
+                    Slog.d(TAG, "New state: mAtRest=" + mAtRest
+                            + ", mRestX=" + mRestX + ", mRestY=" + mRestY + ", mRestZ=" + mRestZ
+                            + ", mTotalSamples=" + mTotalSamples
+                            + ", mMovingSamples=" + mMovingSamples);
+                }
+            }
+        }
+    }
+
+    private void clearAtRestLocked() {
+        mAtRest = false;
+        mRestX = 0;
+        mRestY = 0;
+        mRestZ = 0;
+    }
+
+    private static boolean hasMoved(float x1, float y1, float z1,
+            float x2, float y2, float z2) {
+        final double dotProduct = (x1 * x2) + (y1 * y2) + (z1 * z2);
+        final double mag1 = Math.sqrt((x1 * x1) + (y1 * y1) + (z1 * z1));
+        final double mag2 = Math.sqrt((x2 * x2) + (y2 * y2) + (z2 * z2));
+        if (mag1 < MIN_GRAVITY || mag1 > MAX_GRAVITY
+                || mag2 < MIN_GRAVITY || mag2 > MAX_GRAVITY) {
+            if (DEBUG) {
+                Slog.d(TAG, "Weird gravity vector: mag1=" + mag1 + ", mag2=" + mag2);
+            }
+            return true;
+        }
+        final boolean moved = (dotProduct < mag1 * mag2 * MOVEMENT_ANGLE_COS_THRESHOLD);
+        if (DEBUG) {
+            Slog.d(TAG, "Check: moved=" + moved
+                    + ", x1=" + x1 + ", y1=" + y1 + ", z1=" + z1
+                    + ", x2=" + x2 + ", y2=" + y2 + ", z2=" + z2
+                    + ", angle=" + (Math.acos(dotProduct / mag1 / mag2) * 180 / Math.PI)
+                    + ", dotProduct=" + dotProduct
+                    + ", mag1=" + mag1 + ", mag2=" + mag2);
+        }
+        return moved;
+    }
+
+    private final SensorEventListener mListener = new SensorEventListener() {
+        @Override
+        public void onSensorChanged(SensorEvent event) {
+            processSample(event.timestamp, event.values[0], event.values[1], event.values[2]);
+        }
+
+        @Override
+        public void onAccuracyChanged(Sensor sensor, int accuracy) {
+        }
+    };
+}