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, 7 insertions, 0 deletions

diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index f22792f..dd63a23 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -149,6 +149,11 @@ public:
     static void acquireAudioSessionId(int audioSession, pid_t pid);
     static void releaseAudioSessionId(int audioSession, pid_t pid);
 
+    // Get the HW synchronization source used for an audio session.
+    // Return a valid source or AUDIO_HW_SYNC_INVALID if an error occurs
+    // or no HW sync source is used.
+    static audio_hw_sync_t getAudioHwSyncForSession(audio_session_t sessionId);
+
     // types of io configuration change events received with ioConfigChanged()
     enum io_config_event {
         OUTPUT_OPENED,
diff --git a/include/media/IAudioFlinger.h b/include/media/IAudioFlinger.h
index 82ec09c..31a14f0 100644
--- a/include/media/IAudioFlinger.h
+++ b/include/media/IAudioFlinger.h
@@ -235,6 +235,8 @@ public:
     /* Set audio port configuration */
     virtual status_t setAudioPortConfig(const struct audio_port_config *config) = 0;
 
+    /* Get the HW synchronization source used for an audio session */
+    virtual audio_hw_sync_t getAudioHwSyncForSession(audio_session_t sessionId) = 0;
 };