audioflinger: fix lost offload thread resume event

It was possible that a resume request signaled by addTrack_l()
while waiting for an async write callback is lost. This is because
mSignalPending was not set and waitingAsyncCallback_l() would pause the
thread loop before executing prepareTracks_l().

The fix consists in using signal_l() method to wake the thread
loop o that mSignalPending is set.

Also make sure that sleepTime is reset to 0 when resuming to make sure
that we write any remaining bytes to the HAL.

Bug: 10810347.

Change-Id: If9a3b22cc3b9e6eb384a56c48c40e6258d0896ad

1 files changed, 3 insertions, 1 deletions

diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 3fe470c..b3d88e3 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -526,7 +526,7 @@ private:
     status_t    addTrack_l(const sp<Track>& track);
     bool        destroyTrack_l(const sp<Track>& track);
     void        removeTrack_l(const sp<Track>& track);
-    void        signal_l();
+    void        broadcast_l();
 
     void        readOutputParameters();
 
@@ -590,6 +590,8 @@ private:
     // Bit 0 is reset by the async callback thread calling resetDraining(). Out of sequence
     // callbacks are ignored.
     uint32_t                        mDrainSequence;
+    // A condition that must be evaluated by prepareTrack_l() has changed and we must not wait
+    // for async write callback in the thread loop before evaluating it
     bool                            mSignalPending;
     sp<AsyncCallbackThread>         mCallbackThread;