Simplify enable/disable mixing

The MIXING enum isn't needed, and now returns void instead of status_t.

Change-Id: Ibe4ec24081d75ad4ab78b9c7191fc9077959c4e9
diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index b48f23d..dcc0bd0 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -2197,7 +2197,7 @@
 
             // XXX: these things DON'T need to be done each time
             mAudioMixer->setBufferProvider(track);
-            mAudioMixer->enable(AudioMixer::MIXING);
+            mAudioMixer->enable();
 
             mAudioMixer->setParameter(param, AudioMixer::VOLUME0, (void *)left);
             mAudioMixer->setParameter(param, AudioMixer::VOLUME1, (void *)right);
@@ -2243,7 +2243,7 @@
                     mixerStatus = MIXER_TRACKS_ENABLED;
                 }
             }
-            mAudioMixer->disable(AudioMixer::MIXING);
+            mAudioMixer->disable();
         }
     }
 
diff --git a/services/audioflinger/AudioMixer.cpp b/services/audioflinger/AudioMixer.cpp
index 7c7fa56..8996816 100644
--- a/services/audioflinger/AudioMixer.cpp
+++ b/services/audioflinger/AudioMixer.cpp
@@ -137,36 +137,22 @@
     }
  }
 
-status_t AudioMixer::enable(int name)
+void AudioMixer::enable()
 {
-    switch (name) {
-        case MIXING: {
-            if (mState.tracks[ mActiveTrack ].enabled != 1) {
-                mState.tracks[ mActiveTrack ].enabled = 1;
-                ALOGV("enable(%d)", mActiveTrack);
-                invalidateState(1<<mActiveTrack);
-            }
-        } break;
-        default:
-            return NAME_NOT_FOUND;
+    if (mState.tracks[ mActiveTrack ].enabled != 1) {
+        mState.tracks[ mActiveTrack ].enabled = 1;
+        ALOGV("enable(%d)", mActiveTrack);
+        invalidateState(1<<mActiveTrack);
     }
-    return NO_ERROR;
 }
 
-status_t AudioMixer::disable(int name)
+void AudioMixer::disable()
 {
-    switch (name) {
-        case MIXING: {
-            if (mState.tracks[ mActiveTrack ].enabled != 0) {
-                mState.tracks[ mActiveTrack ].enabled = 0;
-                ALOGV("disable(%d)", mActiveTrack);
-                invalidateState(1<<mActiveTrack);
-            }
-        } break;
-        default:
-            return NAME_NOT_FOUND;
+    if (mState.tracks[ mActiveTrack ].enabled != 0) {
+        mState.tracks[ mActiveTrack ].enabled = 0;
+        ALOGV("disable(%d)", mActiveTrack);
+        invalidateState(1<<mActiveTrack);
     }
-    return NO_ERROR;
 }
 
 status_t AudioMixer::setActiveTrack(int track)
diff --git a/services/audioflinger/AudioMixer.h b/services/audioflinger/AudioMixer.h
index 75c9170..0dc918d 100644
--- a/services/audioflinger/AudioMixer.h
+++ b/services/audioflinger/AudioMixer.h
@@ -50,8 +50,7 @@
         // track units (32 units)
         TRACK0          = 0x1000,
 
-        // enable/disable
-        MIXING          = 0x2000,
+        // 0x2000 is unused
 
         // setParameter targets
         TRACK           = 0x3000,
@@ -78,8 +77,8 @@
     int         getTrackName();
     void        deleteTrackName(int name);
 
-    status_t    enable(int name);
-    status_t    disable(int name);
+    void        enable();
+    void        disable();
 
     status_t    setActiveTrack(int track);
     status_t    setParameter(int target, int name, void *value);