libaudiohal: Handle pause-flush-resume for offloaded streams

Update StreamHalAidl to support pause-flush-resume sequence.
This is implemented by moving the asynchronous output stream
from IDLE back to ACTIVE state by issuing 'burst' command
(see stream-out-async-sm.gv).

Bug: 270552159
Test: atest CtsMediaAudioTestCases:VolumeShaperTest
Change-Id: I810fe817ef648567c30a161f1762343c9bca990b
diff --git a/media/libaudiohal/impl/StreamHalAidl.cpp b/media/libaudiohal/impl/StreamHalAidl.cpp
index 757215d..f9c9f3d 100644
--- a/media/libaudiohal/impl/StreamHalAidl.cpp
+++ b/media/libaudiohal/impl/StreamHalAidl.cpp
@@ -323,6 +323,26 @@
     if (mIsInput) {
         return sendCommand(makeHalCommand<HalCommand::Tag::burst>(0), reply);
     } else {
+        if (mContext.isAsynchronous()) {
+            // Handle pause-flush-resume sequence. 'flush' from PAUSED goes to
+            // IDLE. We move here from IDLE to ACTIVE (same as 'start' from PAUSED).
+            const auto state = getState();
+            if (state == StreamDescriptor::State::IDLE) {
+                StreamDescriptor::Reply localReply{};
+                StreamDescriptor::Reply* innerReply = reply ?: &localReply;
+                if (status_t status =
+                        sendCommand(makeHalCommand<HalCommand::Tag::burst>(0), innerReply);
+                        status != OK) {
+                    return status;
+                }
+                if (innerReply->state != StreamDescriptor::State::ACTIVE) {
+                    ALOGE("%s: unexpected stream state: %s (expected ACTIVE)",
+                            __func__, toString(innerReply->state).c_str());
+                    return INVALID_OPERATION;
+                }
+                return OK;
+            }
+        }
         return sendCommand(makeHalCommand<HalCommand::Tag::start>(), reply);
     }
 }
@@ -514,6 +534,10 @@
 status_t StreamOutHalAidl::setCallback(wp<StreamOutHalInterfaceCallback> callback) {
     TIME_CHECK();
     if (!mStream) return NO_INIT;
+    if (!mContext.isAsynchronous()) {
+        ALOGE("%s: the callback is intended for asynchronous streams only", __func__);
+        return INVALID_OPERATION;
+    }
     if (auto broker = mCallbackBroker.promote(); broker != nullptr) {
         if (auto cb = callback.promote(); cb != nullptr) {
             broker->setStreamOutCallback(this, cb);