diff --git a/media/libaudioclient/AudioSystem.cpp b/media/libaudioclient/AudioSystem.cpp
index 211bd7d..cdc75ac 100644
--- a/media/libaudioclient/AudioSystem.cpp
+++ b/media/libaudioclient/AudioSystem.cpp
@@ -493,14 +493,16 @@
     if (ioDesc == 0 || ioDesc->mIoHandle == AUDIO_IO_HANDLE_NONE) return;
 
     audio_port_handle_t deviceId = AUDIO_PORT_HANDLE_NONE;
-    Vector < sp<AudioDeviceCallback> > callbacks;
+    Vector < wp<AudioDeviceCallback> > callbacks;
 
     {
         Mutex::Autolock _l(mLock);
 
         switch (event) {
         case AUDIO_OUTPUT_OPENED:
-        case AUDIO_INPUT_OPENED: {
+        case AUDIO_OUTPUT_REGISTERED:
+        case AUDIO_INPUT_OPENED:
+        case AUDIO_INPUT_REGISTERED: {
             sp<AudioIoDescriptor> oldDesc = getIoDescriptor_l(ioDesc->mIoHandle);
             if (oldDesc == 0) {
                 mIoDescriptors.add(ioDesc->mIoHandle, ioDesc);
@@ -511,13 +513,19 @@
 
             if (ioDesc->getDeviceId() != AUDIO_PORT_HANDLE_NONE) {
                 deviceId = ioDesc->getDeviceId();
-                ssize_t ioIndex = mAudioDeviceCallbacks.indexOfKey(ioDesc->mIoHandle);
-                if (ioIndex >= 0) {
-                    callbacks = mAudioDeviceCallbacks.valueAt(ioIndex);
+                if (event == AUDIO_OUTPUT_OPENED || event == AUDIO_INPUT_OPENED) {
+                    ssize_t ioIndex = mAudioDeviceCallbacks.indexOfKey(ioDesc->mIoHandle);
+                    if (ioIndex >= 0) {
+                        callbacks = mAudioDeviceCallbacks.valueAt(ioIndex);
+                    }
                 }
             }
-            ALOGV("ioConfigChanged() new %s opened %d samplingRate %u, format %#x channel mask %#x "
-                    "frameCount %zu deviceId %d", event == AUDIO_OUTPUT_OPENED ? "output" : "input",
+            ALOGV("ioConfigChanged() new %s %s %d samplingRate %u, format %#x channel mask %#x "
+                    "frameCount %zu deviceId %d",
+                    event == AUDIO_OUTPUT_OPENED || event == AUDIO_OUTPUT_REGISTERED ?
+                            "output" : "input",
+                            event == AUDIO_OUTPUT_OPENED || event == AUDIO_INPUT_OPENED ?
+                            "opened" : "registered",
                     ioDesc->mIoHandle, ioDesc->mSamplingRate, ioDesc->mFormat, ioDesc->mChannelMask,
                     ioDesc->mFrameCount, ioDesc->getDeviceId());
             } break;
@@ -563,9 +571,23 @@
         } break;
         }
     }
+    bool callbackRemoved = false;
     // callbacks.size() != 0 =>  ioDesc->mIoHandle and deviceId are valid
-    for (size_t i = 0; i < callbacks.size(); i++) {
-        callbacks[i]->onAudioDeviceUpdate(ioDesc->mIoHandle, deviceId);
+    for (size_t i = 0; i < callbacks.size(); ) {
+        sp<AudioDeviceCallback> callback = callbacks[i].promote();
+        if (callback.get() != nullptr) {
+            callback->onAudioDeviceUpdate(ioDesc->mIoHandle, deviceId);
+            i++;
+        } else {
+            callbacks.removeAt(i);
+            callbackRemoved = true;
+        }
+    }
+    // clean up callback list while we are here if some clients have disappeared without
+    // unregistering their callback
+    if (callbackRemoved) {
+        Mutex::Autolock _l(mLock);
+        mAudioDeviceCallbacks.replaceValueFor(ioDesc->mIoHandle, callbacks);
     }
 }
 
@@ -618,17 +640,17 @@
 }
 
 status_t AudioSystem::AudioFlingerClient::addAudioDeviceCallback(
-        const sp<AudioDeviceCallback>& callback, audio_io_handle_t audioIo)
+        const wp<AudioDeviceCallback>& callback, audio_io_handle_t audioIo)
 {
     Mutex::Autolock _l(mLock);
-    Vector < sp<AudioDeviceCallback> > callbacks;
+    Vector < wp<AudioDeviceCallback> > callbacks;
     ssize_t ioIndex = mAudioDeviceCallbacks.indexOfKey(audioIo);
     if (ioIndex >= 0) {
         callbacks = mAudioDeviceCallbacks.valueAt(ioIndex);
     }
 
     for (size_t cbIndex = 0; cbIndex < callbacks.size(); cbIndex++) {
-        if (callbacks[cbIndex] == callback) {
+        if (callbacks[cbIndex].unsafe_get() == callback.unsafe_get()) {
             return INVALID_OPERATION;
         }
     }
@@ -639,18 +661,18 @@
 }
 
 status_t AudioSystem::AudioFlingerClient::removeAudioDeviceCallback(
-        const sp<AudioDeviceCallback>& callback, audio_io_handle_t audioIo)
+        const wp<AudioDeviceCallback>& callback, audio_io_handle_t audioIo)
 {
     Mutex::Autolock _l(mLock);
     ssize_t ioIndex = mAudioDeviceCallbacks.indexOfKey(audioIo);
     if (ioIndex < 0) {
         return INVALID_OPERATION;
     }
-    Vector < sp<AudioDeviceCallback> > callbacks = mAudioDeviceCallbacks.valueAt(ioIndex);
+    Vector < wp<AudioDeviceCallback> > callbacks = mAudioDeviceCallbacks.valueAt(ioIndex);
 
     size_t cbIndex;
     for (cbIndex = 0; cbIndex < callbacks.size(); cbIndex++) {
-        if (callbacks[cbIndex] == callback) {
+        if (callbacks[cbIndex].unsafe_get() == callback.unsafe_get()) {
             break;
         }
     }
@@ -1128,7 +1150,7 @@
 }
 
 status_t AudioSystem::addAudioDeviceCallback(
-        const sp<AudioDeviceCallback>& callback, audio_io_handle_t audioIo)
+        const wp<AudioDeviceCallback>& callback, audio_io_handle_t audioIo)
 {
     const sp<AudioFlingerClient> afc = getAudioFlingerClient();
     if (afc == 0) {
@@ -1145,7 +1167,7 @@
 }
 
 status_t AudioSystem::removeAudioDeviceCallback(
-        const sp<AudioDeviceCallback>& callback, audio_io_handle_t audioIo)
+        const wp<AudioDeviceCallback>& callback, audio_io_handle_t audioIo)
 {
     const sp<AudioFlingerClient> afc = getAudioFlingerClient();
     if (afc == 0) {