diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index cbb216e..932c32b 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -1785,6 +1785,15 @@
     ALOGV("%s(%d)", __func__, mId);
 }
 
+size_t AudioFlinger::PlaybackThread::PatchTrack::framesReady() const
+{
+    if (mPeerProxy && mPeerProxy->producesBufferOnDemand()) {
+        return std::numeric_limits<size_t>::max();
+    } else {
+        return Track::framesReady();
+    }
+}
+
 status_t AudioFlinger::PlaybackThread::PatchTrack::start(AudioSystem::sync_event_t event,
                                                          audio_session_t triggerSession)
 {
@@ -2345,6 +2354,180 @@
     mProxy->releaseBuffer(buffer);
 }
 
+#undef LOG_TAG
+#define LOG_TAG "AF::PthrPatchRecord"
+
+static std::unique_ptr<void, decltype(free)*> allocAligned(size_t alignment, size_t size)
+{
+    void *ptr = nullptr;
+    (void)posix_memalign(&ptr, alignment, size);
+    return std::unique_ptr<void, decltype(free)*>(ptr, free);
+}
+
+AudioFlinger::RecordThread::PassthruPatchRecord::PassthruPatchRecord(
+        RecordThread *recordThread,
+        uint32_t sampleRate,
+        audio_channel_mask_t channelMask,
+        audio_format_t format,
+        size_t frameCount,
+        audio_input_flags_t flags)
+        : PatchRecord(recordThread, sampleRate, channelMask, format, frameCount,
+                nullptr /*buffer*/, 0 /*bufferSize*/, flags),
+          mPatchRecordAudioBufferProvider(*this),
+          mSinkBuffer(allocAligned(32, mFrameCount * mFrameSize)),
+          mStubBuffer(allocAligned(32, mFrameCount * mFrameSize))
+{
+    memset(mStubBuffer.get(), 0, mFrameCount * mFrameSize);
+}
+
+sp<StreamInHalInterface> AudioFlinger::RecordThread::PassthruPatchRecord::obtainStream(
+        sp<ThreadBase>* thread)
+{
+    *thread = mThread.promote();
+    if (!*thread) return nullptr;
+    RecordThread *recordThread = static_cast<RecordThread*>((*thread).get());
+    Mutex::Autolock _l(recordThread->mLock);
+    return recordThread->mInput ? recordThread->mInput->stream : nullptr;
+}
+
+// PatchProxyBufferProvider methods are called on DirectOutputThread
+status_t AudioFlinger::RecordThread::PassthruPatchRecord::obtainBuffer(
+        Proxy::Buffer* buffer, const struct timespec* timeOut)
+{
+    if (mUnconsumedFrames) {
+        buffer->mFrameCount = std::min(buffer->mFrameCount, mUnconsumedFrames);
+        // mUnconsumedFrames is decreased in releaseBuffer to use actual frame consumption figure.
+        return PatchRecord::obtainBuffer(buffer, timeOut);
+    }
+
+    // Otherwise, execute a read from HAL and write into the buffer.
+    nsecs_t startTimeNs = 0;
+    if (timeOut && (timeOut->tv_sec != 0 || timeOut->tv_nsec != 0) && timeOut->tv_sec != INT_MAX) {
+        // Will need to correct timeOut by elapsed time.
+        startTimeNs = systemTime();
+    }
+    const size_t framesToRead = std::min(buffer->mFrameCount, mFrameCount);
+    buffer->mFrameCount = 0;
+    buffer->mRaw = nullptr;
+    sp<ThreadBase> thread;
+    sp<StreamInHalInterface> stream = obtainStream(&thread);
+    if (!stream) return NO_INIT;  // If there is no stream, RecordThread is not reading.
+
+    status_t result = NO_ERROR;
+    struct timespec newTimeOut = *timeOut;
+    size_t bytesRead = 0;
+    {
+        ATRACE_NAME("read");
+        result = stream->read(mSinkBuffer.get(), framesToRead * mFrameSize, &bytesRead);
+        if (result != NO_ERROR) goto stream_error;
+        if (bytesRead == 0) return NO_ERROR;
+    }
+
+    {
+        std::lock_guard<std::mutex> lock(mReadLock);
+        mReadBytes += bytesRead;
+        mReadError = NO_ERROR;
+    }
+    mReadCV.notify_one();
+    // writeFrames handles wraparound and should write all the provided frames.
+    // If it couldn't, there is something wrong with the client/server buffer of the software patch.
+    buffer->mFrameCount = writeFrames(
+            &mPatchRecordAudioBufferProvider,
+            mSinkBuffer.get(), bytesRead / mFrameSize, mFrameSize);
+    ALOGW_IF(buffer->mFrameCount < bytesRead / mFrameSize,
+            "Lost %zu frames obtained from HAL", bytesRead / mFrameSize - buffer->mFrameCount);
+    mUnconsumedFrames = buffer->mFrameCount;
+    // Correct newTimeOut by elapsed time.
+    if (startTimeNs) {
+        nsecs_t newTimeOutNs =
+                audio_utils_ns_from_timespec(&newTimeOut) - (systemTime() - startTimeNs);
+        if (newTimeOutNs < 0) newTimeOutNs = 0;
+        newTimeOut.tv_sec = newTimeOutNs / NANOS_PER_SECOND;
+        newTimeOut.tv_nsec = newTimeOutNs - newTimeOut.tv_sec * NANOS_PER_SECOND;
+    }
+    return PatchRecord::obtainBuffer(buffer, &newTimeOut);
+
+stream_error:
+    stream->standby();
+    {
+        std::lock_guard<std::mutex> lock(mReadLock);
+        mReadError = result;
+    }
+    mReadCV.notify_one();
+    return result;
+}
+
+void AudioFlinger::RecordThread::PassthruPatchRecord::releaseBuffer(Proxy::Buffer* buffer)
+{
+    if (buffer->mFrameCount <= mUnconsumedFrames) {
+        mUnconsumedFrames -= buffer->mFrameCount;
+    } else {
+        ALOGW("Write side has consumed more frames than we had: %zu > %zu",
+                buffer->mFrameCount, mUnconsumedFrames);
+        mUnconsumedFrames = 0;
+    }
+    PatchRecord::releaseBuffer(buffer);
+}
+
+// AudioBufferProvider and Source methods are called on RecordThread
+// 'read' emulates actual audio data with 0's. This is OK as 'getNextBuffer'
+// and 'releaseBuffer' are stubbed out and ignore their input.
+// It's not possible to retrieve actual data here w/o blocking 'obtainBuffer'
+// until we copy it.
+status_t AudioFlinger::RecordThread::PassthruPatchRecord::read(
+        void* buffer, size_t bytes, size_t* read)
+{
+    bytes = std::min(bytes, mFrameCount * mFrameSize);
+    {
+        std::unique_lock<std::mutex> lock(mReadLock);
+        mReadCV.wait(lock, [&]{ return mReadError != NO_ERROR || mReadBytes != 0; });
+        if (mReadError != NO_ERROR) {
+            mLastReadFrames = 0;
+            return mReadError;
+        }
+        *read = std::min(bytes, mReadBytes);
+        mReadBytes -= *read;
+    }
+    mLastReadFrames = *read / mFrameSize;
+    memset(buffer, 0, *read);
+    return 0;
+}
+
+status_t AudioFlinger::RecordThread::PassthruPatchRecord::getCapturePosition(
+        int64_t* frames, int64_t* time)
+{
+    sp<ThreadBase> thread;
+    sp<StreamInHalInterface> stream = obtainStream(&thread);
+    return stream ? stream->getCapturePosition(frames, time) : NO_INIT;
+}
+
+status_t AudioFlinger::RecordThread::PassthruPatchRecord::standby()
+{
+    // RecordThread issues 'standby' command in two major cases:
+    // 1. Error on read--this case is handled in 'obtainBuffer'.
+    // 2. Track is stopping--as PassthruPatchRecord assumes continuous
+    //    output, this can only happen when the software patch
+    //    is being torn down. In this case, the RecordThread
+    //    will terminate and close the HAL stream.
+    return 0;
+}
+
+// As the buffer gets filled in obtainBuffer, here we only simulate data consumption.
+status_t AudioFlinger::RecordThread::PassthruPatchRecord::getNextBuffer(
+        AudioBufferProvider::Buffer* buffer)
+{
+    buffer->frameCount = mLastReadFrames;
+    buffer->raw = buffer->frameCount != 0 ? mStubBuffer.get() : nullptr;
+    return NO_ERROR;
+}
+
+void AudioFlinger::RecordThread::PassthruPatchRecord::releaseBuffer(
+        AudioBufferProvider::Buffer* buffer)
+{
+    buffer->frameCount = 0;
+    buffer->raw = nullptr;
+}
+
 // ----------------------------------------------------------------------------
 #undef LOG_TAG
 #define LOG_TAG "AF::MmapTrack"