diff --git a/services/audioflinger/AudioMixer.cpp b/services/audioflinger/AudioMixer.cpp
index d32f4d1..805eaa4 100644
--- a/services/audioflinger/AudioMixer.cpp
+++ b/services/audioflinger/AudioMixer.cpp
@@ -159,7 +159,6 @@
     if (names != 0) {
         int n = __builtin_ctz(names);
         ALOGV("add track (%d)", n);
-        mTrackNames |= 1 << n;
         // assume default parameters for the track, except where noted below
         track_t* t = &mState.tracks[n];
         t->needs = 0;
@@ -175,10 +174,10 @@
         // no initialization needed
         // t->prevAuxLevel
         // t->frameCount
-        t->channelCount = 2;
+        t->channelCount = audio_channel_count_from_out_mask(channelMask);
         t->enabled = false;
         t->format = 16;
-        t->channelMask = AUDIO_CHANNEL_OUT_STEREO;
+        t->channelMask = channelMask;
         t->sessionId = sessionId;
         // setBufferProvider(name, AudioBufferProvider *) is required before enable(name)
         t->bufferProvider = NULL;
@@ -196,12 +195,14 @@
         t->mMixerFormat = AUDIO_FORMAT_PCM_16_BIT;
 
         status_t status = initTrackDownmix(&mState.tracks[n], n, channelMask);
-        if (status == OK) {
-            return TRACK0 + n;
+        if (status != OK) {
+            ALOGE("AudioMixer::getTrackName invalid channelMask (%#x)", channelMask);
+            return -1;
         }
-        ALOGE("AudioMixer::getTrackName(0x%x) failed, error preparing track for downmix",
-                channelMask);
+        mTrackNames |= 1 << n;
+        return TRACK0 + n;
     }
+    ALOGE("AudioMixer::getTrackName out of available tracks");
     return -1;
 }
 
diff --git a/services/audioflinger/FastMixer.cpp b/services/audioflinger/FastMixer.cpp
index 42ba791..1caed11 100644
--- a/services/audioflinger/FastMixer.cpp
+++ b/services/audioflinger/FastMixer.cpp
@@ -224,17 +224,13 @@
             AudioBufferProvider *bufferProvider = fastTrack->mBufferProvider;
             ALOG_ASSERT(bufferProvider != NULL && fastTrackNames[i] == -1);
             if (mixer != NULL) {
-                // calling getTrackName with default channel mask and a random invalid
-                //   sessionId (no effects here)
-                name = mixer->getTrackName(AUDIO_CHANNEL_OUT_STEREO, -555);
+                name = mixer->getTrackName(fastTrack->mChannelMask, AUDIO_SESSION_OUTPUT_MIX);
                 ALOG_ASSERT(name >= 0);
                 fastTrackNames[i] = name;
                 mixer->setBufferProvider(name, bufferProvider);
                 mixer->setParameter(name, AudioMixer::TRACK, AudioMixer::MAIN_BUFFER,
                         (void *) mixBuffer);
                 // newly allocated track names default to full scale volume
-                mixer->setParameter(name, AudioMixer::TRACK, AudioMixer::CHANNEL_MASK,
-                        (void *)(uintptr_t)fastTrack->mChannelMask);
                 mixer->enable(name);
             }
             generations[i] = fastTrack->mGeneration;