AudioSystem: add API to query audio HW sync source

Add a method to query from the audio HAL the HW sync
source used for a given audio session.
Modify audio policy to select a direct output with HW sync
when requested.

Bug: 16132368.

Change-Id: I03038f9188f2d389f8a5fd76a671854013a4513e

2 files changed, 22 insertions, 0 deletions

diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index b8cc33a..1f77b2f 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -1579,6 +1579,25 @@ status_t AudioFlinger::setLowRamDevice(bool isLowRamDevice)
     return NO_ERROR;
 }
 
+audio_hw_sync_t AudioFlinger::getAudioHwSyncForSession(audio_session_t sessionId)
+{
+    Mutex::Autolock _l(mLock);
+    for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
+        sp<PlaybackThread> thread = mPlaybackThreads.valueAt(i);
+        if ((thread->hasAudioSession(sessionId) & ThreadBase::TRACK_SESSION) != 0) {
+            // A session can only be on one thread, so exit after first match
+            String8 reply = thread->getParameters(String8(AUDIO_PARAMETER_STREAM_HW_AV_SYNC));
+            AudioParameter param = AudioParameter(reply);
+            int value;
+            if (param.getInt(String8(AUDIO_PARAMETER_STREAM_HW_AV_SYNC), value) == NO_ERROR) {
+                return value;
+            }
+            break;
+        }
+    }
+    return AUDIO_HW_SYNC_INVALID;
+}
+
 // ----------------------------------------------------------------------------
 
 
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 31c5a1a..4e9d49b 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -248,6 +248,9 @@ public:
     /* Set audio port configuration */
     virtual status_t setAudioPortConfig(const struct audio_port_config *config);
 
+    /* Get the HW synchronization source used for an audio session */
+    virtual audio_hw_sync_t getAudioHwSyncForSession(audio_session_t sessionId);
+
     virtual     status_t    onTransact(
                                 uint32_t code,
                                 const Parcel& data,