audioflinger: fix standby delay on A2DP output

Make sure that standby delay is never less than the audio flinger
default on A2DP output.
Due to variable latency and amount of buffering in A2DP sinks,
an agressive standby delay could lead to truncated audio.

Bug: 25830539.
Change-Id: I38be37ad346f5f4bf8303d3db4e3e911bf637968
(cherry picked from commit 42537be61479e59c4718e1304364551c1454f63c)

1 files changed, 20 insertions, 3 deletions

diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 71fc498..7d2d550 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -1589,6 +1589,7 @@ void AudioFlinger::PlaybackThread::dumpInternals(int fd, const Vector<String16>&
     dprintf(fd, "  Mixer buffer: %p\n", mMixerBuffer);
     dprintf(fd, "  Effect buffer: %p\n", mEffectBuffer);
     dprintf(fd, "  Fast track availMask=%#x\n", mFastTrackAvailMask);
+    dprintf(fd, "  Standby delay ns=%lld\n", (long long)mStandbyDelayNs);
     AudioStreamOut *output = mOutput;
     audio_output_flags_t flags = output != NULL ? output->flags : AUDIO_OUTPUT_FLAG_NONE;
     String8 flagsAsString = outputFlagsToString(flags);
@@ -2513,7 +2514,8 @@ The derived values that are cached:
  - mSinkBufferSize from frame count * frame size
  - mActiveSleepTimeUs from activeSleepTimeUs()
  - mIdleSleepTimeUs from idleSleepTimeUs()
- - mStandbyDelayNs from mActiveSleepTimeUs (DIRECT only)
+ - mStandbyDelayNs from mActiveSleepTimeUs (DIRECT only) or forced to at least
+   kDefaultStandbyTimeInNsecs when connected to an A2DP device.
  - maxPeriod from frame count and sample rate (MIXER only)
 
 The parameters that affect these derived values are:
@@ -2532,6 +2534,15 @@ void AudioFlinger::PlaybackThread::cacheParameters_l()
     mSinkBufferSize = mNormalFrameCount * mFrameSize;
     mActiveSleepTimeUs = activeSleepTimeUs();
     mIdleSleepTimeUs = idleSleepTimeUs();
+
+    // make sure standby delay is not too short when connected to an A2DP sink to avoid
+    // truncating audio when going to standby.
+    mStandbyDelayNs = AudioFlinger::mStandbyTimeInNsecs;
+    if ((mOutDevice & AUDIO_DEVICE_OUT_ALL_A2DP) != 0) {
+        if (mStandbyDelayNs < kDefaultStandbyTimeInNsecs) {
+            mStandbyDelayNs = kDefaultStandbyTimeInNsecs;
+        }
+    }
 }
 
 void AudioFlinger::PlaybackThread::invalidateTracks(audio_stream_type_t streamType)
@@ -4248,6 +4259,7 @@ bool AudioFlinger::MixerThread::checkForNewParameter_l(const String8& keyValuePa
                                                        status_t& status)
 {
     bool reconfig = false;
+    bool a2dpDeviceChanged = false;
 
     status = NO_ERROR;
 
@@ -4324,6 +4336,8 @@ bool AudioFlinger::MixerThread::checkForNewParameter_l(const String8& keyValuePa
         // forward device change to effects that have requested to be
         // aware of attached audio device.
         if (value != AUDIO_DEVICE_NONE) {
+            a2dpDeviceChanged =
+                    (mOutDevice & AUDIO_DEVICE_OUT_ALL_A2DP) != (value & AUDIO_DEVICE_OUT_ALL_A2DP);
             mOutDevice = value;
             for (size_t i = 0; i < mEffectChains.size(); i++) {
                 mEffectChains[i]->setDevice_l(mOutDevice);
@@ -4367,7 +4381,7 @@ bool AudioFlinger::MixerThread::checkForNewParameter_l(const String8& keyValuePa
         sq->push(FastMixerStateQueue::BLOCK_UNTIL_PUSHED);
     }
 
-    return reconfig;
+    return reconfig || a2dpDeviceChanged;
 }
 
 
@@ -4803,6 +4817,7 @@ bool AudioFlinger::DirectOutputThread::checkForNewParameter_l(const String8& key
                                                               status_t& status)
 {
     bool reconfig = false;
+    bool a2dpDeviceChanged = false;
 
     status = NO_ERROR;
 
@@ -4812,6 +4827,8 @@ bool AudioFlinger::DirectOutputThread::checkForNewParameter_l(const String8& key
         // forward device change to effects that have requested to be
         // aware of attached audio device.
         if (value != AUDIO_DEVICE_NONE) {
+            a2dpDeviceChanged =
+                    (mOutDevice & AUDIO_DEVICE_OUT_ALL_A2DP) != (value & AUDIO_DEVICE_OUT_ALL_A2DP);
             mOutDevice = value;
             for (size_t i = 0; i < mEffectChains.size(); i++) {
                 mEffectChains[i]->setDevice_l(mOutDevice);
@@ -4844,7 +4861,7 @@ bool AudioFlinger::DirectOutputThread::checkForNewParameter_l(const String8& key
         }
     }
 
-    return reconfig;
+    return reconfig || a2dpDeviceChanged;
 }
 
 uint32_t AudioFlinger::DirectOutputThread::activeSleepTimeUs() const