audiolfinger: implement latency mode control in spatializer mixer

Add audio HAL stream latency mode control logic to
Spatialier mixer thread:
- Query supported latency modes from HAL stream and register mode
change callback: when mode changes either from callback or routing
change, notify Spatializer effect client via IAudioFlingerClient
interface.
- Compute requested latency mode based on the requested mode and
active spatialized tracks and request it from HAL stream.

Bug: 218273231
Test: make
Change-Id: Ifc4445e1ce554631dbcffaf478fbe8a33ec1b5ab
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 747a1bf..c77d662 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -741,6 +741,12 @@
     sendConfigEvent_l(configEvent);
 }
 
+void AudioFlinger::ThreadBase::sendHalLatencyModesChangedEvent_l()
+{
+    sp<ConfigEvent> configEvent = sp<HalLatencyModesChangedEvent>::make();
+    sendConfigEvent_l(configEvent);
+}
+
 // post condition: mConfigEvents.isEmpty()
 void AudioFlinger::ThreadBase::processConfigEvents_l()
 {
@@ -808,6 +814,10 @@
             setCheckOutputStageEffects();
         } break;
 
+        case CFG_EVENT_HAL_LATENCY_MODES_CHANGED: {
+            onHalLatencyModesChanged_l();
+        } break;
+
         default:
             ALOG_ASSERT(false, "processConfigEvents_l() unknown event type %d", event->mType);
             break;
@@ -3919,6 +3929,8 @@
             // stop(), pause(), etc.), but the threadLoop is entitled to call audio
             // data / buffer methods on tracks from activeTracks without the ThreadBase lock.
             activeTracks.insert(activeTracks.end(), mActiveTracks.begin(), mActiveTracks.end());
+
+            setHalLatencyMode_l();
         } // mLock scope ends
 
         if (mBytesRemaining == 0) {
@@ -5018,6 +5030,7 @@
         mCallbackThread->setDraining(mDrainSequence);
     }
     mHwPaused = false;
+    setHalLatencyMode_l();
 }
 
 void AudioFlinger::PlaybackThread::onAddNewTrack_l()
@@ -7261,6 +7274,94 @@
 {
 }
 
+void AudioFlinger::SpatializerThread::onFirstRef() {
+    PlaybackThread::onFirstRef();
+
+    Mutex::Autolock _l(mLock);
+    status_t status = mOutput->stream->setLatencyModeCallback(this);
+    if (status != INVALID_OPERATION) {
+        updateHalSupportedLatencyModes_l();
+    }
+}
+
+status_t AudioFlinger::SpatializerThread::createAudioPatch_l(const struct audio_patch *patch,
+                                                          audio_patch_handle_t *handle)
+{
+    status_t status = MixerThread::createAudioPatch_l(patch, handle);
+    updateHalSupportedLatencyModes_l();
+    return status;
+}
+
+void AudioFlinger::SpatializerThread::updateHalSupportedLatencyModes_l() {
+    std::vector<audio_latency_mode_t> latencyModes;
+    if (mOutput->stream->getRecommendedLatencyModes(&latencyModes) != NO_ERROR) {
+        latencyModes.clear();
+    }
+    if (latencyModes != mSupportedLatencyModes) {
+        mSupportedLatencyModes.swap(latencyModes);
+        sendHalLatencyModesChangedEvent_l();
+    }
+}
+
+void AudioFlinger::SpatializerThread::onHalLatencyModesChanged_l() {
+    mAudioFlinger->onSupportedLatencyModesChanged(mId, mSupportedLatencyModes);
+}
+
+void AudioFlinger::SpatializerThread::setHalLatencyMode_l() {
+    // if mSupportedLatencyModes is empty, the HAL stream does not support
+    // latency mode control and we can exit.
+    if (mSupportedLatencyModes.empty()) {
+        return;
+    }
+    audio_latency_mode_t latencyMode = AUDIO_LATENCY_MODE_FREE;
+    if (mSupportedLatencyModes.size() == 1) {
+        // If the HAL only support one latency mode currently, confirm the choice
+        latencyMode = mSupportedLatencyModes[0];
+    } else if (mSupportedLatencyModes.size() > 1) {
+        // Request low latency if:
+        // - The low latency mode is requested by the spatializer controller
+        //   (mRequestedLatencyMode = AUDIO_LATENCY_MODE_LOW)
+        //      AND
+        // - At least one active track is spatialized
+        bool hasSpatializedActiveTrack = false;
+        for (const auto& track : mActiveTracks) {
+            if (track->isSpatialized()) {
+                hasSpatializedActiveTrack = true;
+                break;
+            }
+        }
+        if (hasSpatializedActiveTrack && mRequestedLatencyMode == AUDIO_LATENCY_MODE_LOW) {
+            latencyMode = AUDIO_LATENCY_MODE_LOW;
+        }
+    }
+
+    if (latencyMode != mSetLatencyMode) {
+        status_t status = mOutput->stream->setLatencyMode(latencyMode);
+        if (status == NO_ERROR) {
+            mSetLatencyMode = latencyMode;
+        }
+    }
+}
+
+status_t AudioFlinger::SpatializerThread::setRequestedLatencyMode(audio_latency_mode_t mode) {
+    if (mode != AUDIO_LATENCY_MODE_LOW && mode != AUDIO_LATENCY_MODE_FREE) {
+        return BAD_VALUE;
+    }
+    Mutex::Autolock _l(mLock);
+    mRequestedLatencyMode = mode;
+    return NO_ERROR;
+}
+
+status_t AudioFlinger::SpatializerThread::getSupportedLatencyModes(
+        std::vector<audio_latency_mode_t>* modes) {
+    if (modes == nullptr) {
+        return BAD_VALUE;
+    }
+    Mutex::Autolock _l(mLock);
+    *modes = mSupportedLatencyModes;
+    return NO_ERROR;
+}
+
 void AudioFlinger::SpatializerThread::checkOutputStageEffects()
 {
     bool hasVirtualizer = false;
@@ -7313,6 +7414,14 @@
     }
 }
 
+void AudioFlinger::SpatializerThread::onRecommendedLatencyModeChanged(
+        std::vector<audio_latency_mode_t> modes) {
+    Mutex::Autolock _l(mLock);
+    if (modes != mSupportedLatencyModes) {
+        mSupportedLatencyModes.swap(modes);
+        sendHalLatencyModesChangedEvent_l();
+    }
+}
 
 // ----------------------------------------------------------------------------
 //      Record