Audio HAL V7.1: Add latency mode APIs

Add APis for controlling the latency mode on an output stream.
Latency mode control is optional but mandated if spatial audio with
head tracking is supported over Bluetooth classic audio link.

Bug: 187446271
Test: m android.hardware.audio@7.1-impl
Change-Id: I363db3bf7f7b6439e326d0f6f4becc10b3947e7d

audio/7.1/Android.bp

@@ -13,11 +13,13 @@ hidl_interface {
     name: "android.hardware.audio@7.1",
     root: "android.hardware",
     srcs: [
+        "types.hal",
         "IDevice.hal",
         "IDevicesFactory.hal",
         "IPrimaryDevice.hal",
         "IStreamIn.hal",
         "IStreamOut.hal",
+        "IStreamOutLatencyModeCallback.hal",
     ],
     interfaces: [
         "android.hardware.audio@7.0",

audio/7.1/IStreamOut.hal

@@ -16,7 +16,54 @@
 
 package android.hardware.audio@7.1;
 
+import @7.0::Result;
 import @7.0::IStreamOut;
 
+import IStreamOutLatencyModeCallback;
+
 interface IStreamOut extends @7.0::IStreamOut {
+    /**
+     * Indicates the requested latency mode for this output stream.
+     *
+     * The requested mode can be one of the modes returned by
+     * getRecommendedLatencyModes() API.
+     *
+     * Optional method.
+     * Mandated only on specific spatial audio streams indicated by
+     * AUDIO_OUTPUT_FLAG_SPATIALIZER flag if they can be routed to a BT classic sink.
+     *
+     * @return retval operation completion status.
+     */
+    setLatencyMode(LatencyMode mode) generates (Result retval);
+
+    /**
+     * Indicates which latency modes are currently supported on this output stream.
+     * If the transport protocol (e.g Bluetooth A2DP) used by this output stream to reach
+     * the output device supports variable latency modes, the HAL indicates which
+     * modes are currently supported.
+     * The framework can then call setLatencyMode() with one of the supported modes to select
+     * the desired operation mode.
+     *
+     * Optional method.
+     * Mandated only on specific spatial audio streams indicated by
+     * AUDIO_OUTPUT_FLAG_SPATIALIZER flag if they can be routed to a BT classic sink.
+     *
+     * @return retval operation completion status.
+     * @return modes currrently supported latency modes.
+     */
+    getRecommendedLatencyModes() generates (Result retval, vec<LatencyMode> modes);
+
+    /**
+     * Set the callback interface for notifying changes in supported latency modes.
+     *
+     * Calling this method with a null pointer will result in releasing
+     * the callback.
+     *
+     * Optional method.
+     * Mandated only on specific spatial audio streams indicated by
+     * AUDIO_OUTPUT_FLAG_SPATIALIZER flag if they can be routed to a BT classic sink.
+     *
+     * @return retval operation completion status.
+     */
+    setLatencyModeCallback(IStreamOutLatencyModeCallback callback) generates (Result retval);
 };

audio/7.1/IStreamOutLatencyModeCallback.hal

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+package android.hardware.audio@7.1;
+
+/**
+ * Callback interface for output stream variable latency mode feature.
+ */
+interface IStreamOutLatencyModeCallback {
+    /**
+     * Called with the new list of supported latency modes when a change occurs.
+     */
+    oneway onRecommendedLatencyModeChanged(vec<LatencyMode> modes);
+};

audio/7.1/types.hal

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.hardware.audio@7.1;
+
+/**
+ * Latency modes used for the variable latency feature on output streams.
+ * Used by setLatencyMode() and getRecommendedLatencyModes() methods.
+ */
+
+@export(name="audio_latency_mode_t", value_prefix="AUDIO_LATENCY_MODE_")
+enum LatencyMode : int32_t {
+    /** No specific constraint on the latency */
+    FREE = 0,
+    /** A relatively low latency compatible with head tracking operation (e.g less than 100ms) */
+    LOW = 1,
+};

audio/core/all-versions/default/StreamOut.cpp

@@ -761,6 +761,73 @@ int StreamOut::asyncEventCallback(stream_event_callback_type_t event, void* para
     ALOGW_IF(!result.isOk(), "Client callback failed: %s", result.description().c_str());
     return 0;
 }
+
+#if MAJOR_VERSION == 7 && MINOR_VERSION == 1
+Return<Result> StreamOut::setLatencyMode(LatencyMode mode) {
+    return mStream->set_latency_mode != nullptr
+                   ? Stream::analyzeStatus(
+                             "set_latency_mode",
+                             mStream->set_latency_mode(mStream,
+                                                       static_cast<audio_latency_mode_t>(mode)))
+                   : Result::NOT_SUPPORTED;
+};
+
+Return<void> StreamOut::getRecommendedLatencyModes(getRecommendedLatencyModes_cb _hidl_cb) {
+    Result retval = Result::NOT_SUPPORTED;
+    hidl_vec<LatencyMode> hidlModes;
+    size_t num_modes = AUDIO_LATENCY_MODE_CNT;
+    audio_latency_mode_t modes[AUDIO_LATENCY_MODE_CNT];
+
+    if (mStream->get_recommended_latency_modes != nullptr &&
+        mStream->get_recommended_latency_modes(mStream, &modes[0], &num_modes) == 0) {
+        if (num_modes == 0 || num_modes > AUDIO_LATENCY_MODE_CNT) {
+            ALOGW("%s invalid number of modes returned: %zu", __func__, num_modes);
+            retval = Result::INVALID_STATE;
+        } else {
+            hidlModes.resize(num_modes);
+            for (size_t i = 0; i < num_modes; ++i) {
+                hidlModes[i] = static_cast<LatencyMode>(modes[i]);
+            }
+            retval = Result::OK;
+        }
+    }
+    _hidl_cb(retval, hidlModes);
+    return Void();
+};
+
+// static
+void StreamOut::latencyModeCallback(audio_latency_mode_t* modes, size_t num_modes, void* cookie) {
+    StreamOut* self = reinterpret_cast<StreamOut*>(cookie);
+    sp<IStreamOutLatencyModeCallback> callback = self->mLatencyModeCallback.load();
+    if (callback.get() == nullptr) return;
+
+    ALOGV("%s", __func__);
+
+    if (num_modes == 0 || num_modes > AUDIO_LATENCY_MODE_CNT) {
+        ALOGW("%s invalid number of modes returned: %zu", __func__, num_modes);
+        return;
+    }
+
+    hidl_vec<LatencyMode> hidlModes(num_modes);
+    for (size_t i = 0; i < num_modes; ++i) {
+        hidlModes[i] = static_cast<LatencyMode>(modes[i]);
+    }
+    Return<void> result = callback->onRecommendedLatencyModeChanged(hidlModes);
+    ALOGW_IF(!result.isOk(), "Client callback failed: %s", result.description().c_str());
+}
+
+Return<Result> StreamOut::setLatencyModeCallback(
+        const sp<IStreamOutLatencyModeCallback>& callback) {
+    if (mStream->set_latency_mode_callback == nullptr) return Result::NOT_SUPPORTED;
+    int result = mStream->set_latency_mode_callback(mStream, StreamOut::latencyModeCallback, this);
+    if (result == 0) {
+        mLatencyModeCallback = callback;
+    }
+    return Stream::analyzeStatus("set_latency_mode_callback", result, {ENOSYS} /*ignore*/);
+};
+
+#endif
+
 #endif
 
 }  // namespace implementation

audio/core/all-versions/default/include/core/default/StreamOut.h

@@ -153,6 +153,12 @@ struct StreamOut : public IStreamOut {
     Result doUpdateSourceMetadata(const SourceMetadata& sourceMetadata);
 #if MAJOR_VERSION >= 7
     Result doUpdateSourceMetadataV7(const SourceMetadata& sourceMetadata);
+#if MAJOR_VERSION == 7 && MINOR_VERSION == 1
+    Return<Result> setLatencyMode(LatencyMode mode) override;
+    Return<void> getRecommendedLatencyModes(getRecommendedLatencyModes_cb _hidl_cb) override;
+    Return<Result> setLatencyModeCallback(
+            const sp<IStreamOutLatencyModeCallback>& callback) override;
+#endif
 #endif
 #endif  // MAJOR_VERSION >= 4
 
@@ -163,6 +169,9 @@ struct StreamOut : public IStreamOut {
     mediautils::atomic_sp<IStreamOutCallback> mCallback;  // for non-blocking write and drain
 #if MAJOR_VERSION >= 6
     mediautils::atomic_sp<IStreamOutEventCallback> mEventCallback;
+#if MAJOR_VERSION == 7 && MINOR_VERSION == 1
+    mediautils::atomic_sp<IStreamOutLatencyModeCallback> mLatencyModeCallback;
+#endif
 #endif
     std::unique_ptr<CommandMQ> mCommandMQ;
     std::unique_ptr<DataMQ> mDataMQ;
@@ -177,6 +186,9 @@ struct StreamOut : public IStreamOut {
 
 #if MAJOR_VERSION >= 6
     static int asyncEventCallback(stream_event_callback_type_t event, void* param, void* cookie);
+#if MAJOR_VERSION == 7 && MINOR_VERSION == 1
+    static void latencyModeCallback(audio_latency_mode_t* modes, size_t num_modes, void* cookie);
+#endif
 #endif
 };