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1 /*
2  * Copyright (C) 2012 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 // <IMPORTANT_WARNING>
18 // Design rules for threadLoop() are given in the comments at section "Fast mixer thread" of
19 // StateQueue.h.  In particular, avoid library and system calls except at well-known points.
20 // The design rules are only for threadLoop(), and don't apply to FastMixerDumpState methods.
21 // </IMPORTANT_WARNING>
22 
23 #define LOG_TAG "FastMixer"
24 //#define LOG_NDEBUG 0
25 
26 #define ATRACE_TAG ATRACE_TAG_AUDIO
27 
28 #include "Configuration.h"
29 #include <time.h>
30 #include <utils/Log.h>
31 #include <utils/Trace.h>
32 #include <system/audio.h>
33 #ifdef FAST_THREAD_STATISTICS
34 #include <audio_utils/Statistics.h>
35 #ifdef CPU_FREQUENCY_STATISTICS
36 #include <cpustats/ThreadCpuUsage.h>
37 #endif
38 #endif
39 #include <audio_utils/channels.h>
40 #include <audio_utils/format.h>
41 #include <audio_utils/mono_blend.h>
42 #include <cutils/bitops.h>
43 #include <media/AudioMixer.h>
44 #include "FastMixer.h"
45 #include "TypedLogger.h"
46 
47 namespace android {
48 
49 /*static*/ const FastMixerState FastMixer::sInitial;
50 
getChannelMaskFromCount(size_t count)51 static audio_channel_mask_t getChannelMaskFromCount(size_t count) {
52     const audio_channel_mask_t mask = audio_channel_out_mask_from_count(count);
53     if (mask == AUDIO_CHANNEL_INVALID) {
54         // some counts have no positional masks. TODO: Update this to return index count?
55         return audio_channel_mask_for_index_assignment_from_count(count);
56     }
57     return mask;
58 }
59 
FastMixer(audio_io_handle_t parentIoHandle)60 FastMixer::FastMixer(audio_io_handle_t parentIoHandle)
61     : FastThread("cycle_ms", "load_us"),
62     // mFastTrackNames
63     // mGenerations
64     mOutputSink(NULL),
65     mOutputSinkGen(0),
66     mMixer(NULL),
67     mSinkBuffer(NULL),
68     mSinkBufferSize(0),
69     mSinkChannelCount(FCC_2),
70     mMixerBuffer(NULL),
71     mMixerBufferSize(0),
72     mMixerBufferState(UNDEFINED),
73     mFormat(Format_Invalid),
74     mSampleRate(0),
75     mFastTracksGen(0),
76     mTotalNativeFramesWritten(0),
77     // timestamp
78     mNativeFramesWrittenButNotPresented(0),   // the = 0 is to silence the compiler
79     mMasterMono(false),
80     mThreadIoHandle(parentIoHandle)
81 {
82     (void)mThreadIoHandle; // prevent unused warning, see C++17 [[maybe_unused]]
83 
84     // FIXME pass sInitial as parameter to base class constructor, and make it static local
85     mPrevious = &sInitial;
86     mCurrent = &sInitial;
87 
88     mDummyDumpState = &mDummyFastMixerDumpState;
89     // TODO: Add channel mask to NBAIO_Format.
90     // We assume that the channel mask must be a valid positional channel mask.
91     mSinkChannelMask = getChannelMaskFromCount(mSinkChannelCount);
92 
93     unsigned i;
94     for (i = 0; i < FastMixerState::sMaxFastTracks; ++i) {
95         mGenerations[i] = 0;
96     }
97 #ifdef FAST_THREAD_STATISTICS
98     mOldLoad.tv_sec = 0;
99     mOldLoad.tv_nsec = 0;
100 #endif
101 }
102 
~FastMixer()103 FastMixer::~FastMixer()
104 {
105 }
106 
sq()107 FastMixerStateQueue* FastMixer::sq()
108 {
109     return &mSQ;
110 }
111 
poll()112 const FastThreadState *FastMixer::poll()
113 {
114     return mSQ.poll();
115 }
116 
setNBLogWriter(NBLog::Writer * logWriter __unused)117 void FastMixer::setNBLogWriter(NBLog::Writer *logWriter __unused)
118 {
119 }
120 
onIdle()121 void FastMixer::onIdle()
122 {
123     mPreIdle = *(const FastMixerState *)mCurrent;
124     mCurrent = &mPreIdle;
125 }
126 
onExit()127 void FastMixer::onExit()
128 {
129     delete mMixer;
130     free(mMixerBuffer);
131     free(mSinkBuffer);
132 }
133 
isSubClassCommand(FastThreadState::Command command)134 bool FastMixer::isSubClassCommand(FastThreadState::Command command)
135 {
136     switch ((FastMixerState::Command) command) {
137     case FastMixerState::MIX:
138     case FastMixerState::WRITE:
139     case FastMixerState::MIX_WRITE:
140         return true;
141     default:
142         return false;
143     }
144 }
145 
updateMixerTrack(int index,Reason reason)146 void FastMixer::updateMixerTrack(int index, Reason reason) {
147     const FastMixerState * const current = (const FastMixerState *) mCurrent;
148     const FastTrack * const fastTrack = &current->mFastTracks[index];
149 
150     // check and update generation
151     if (reason == REASON_MODIFY && mGenerations[index] == fastTrack->mGeneration) {
152         return; // no change on an already configured track.
153     }
154     mGenerations[index] = fastTrack->mGeneration;
155 
156     // mMixer == nullptr on configuration failure (check done after generation update).
157     if (mMixer == nullptr) {
158         return;
159     }
160 
161     switch (reason) {
162     case REASON_REMOVE:
163         mMixer->destroy(index);
164         break;
165     case REASON_ADD: {
166         const status_t status = mMixer->create(
167                 index, fastTrack->mChannelMask, fastTrack->mFormat, AUDIO_SESSION_OUTPUT_MIX);
168         LOG_ALWAYS_FATAL_IF(status != NO_ERROR,
169                 "%s: cannot create fast track index"
170                 " %d, mask %#x, format %#x in AudioMixer",
171                 __func__, index, fastTrack->mChannelMask, fastTrack->mFormat);
172     }
173         [[fallthrough]];  // now fallthrough to update the newly created track.
174     case REASON_MODIFY:
175         mMixer->setBufferProvider(index, fastTrack->mBufferProvider);
176 
177         float vlf, vrf;
178         if (fastTrack->mVolumeProvider != nullptr) {
179             const gain_minifloat_packed_t vlr = fastTrack->mVolumeProvider->getVolumeLR();
180             vlf = float_from_gain(gain_minifloat_unpack_left(vlr));
181             vrf = float_from_gain(gain_minifloat_unpack_right(vlr));
182         } else {
183             vlf = vrf = AudioMixer::UNITY_GAIN_FLOAT;
184         }
185 
186         // set volume to avoid ramp whenever the track is updated (or created).
187         // Note: this does not distinguish from starting fresh or
188         // resuming from a paused state.
189         mMixer->setParameter(index, AudioMixer::VOLUME, AudioMixer::VOLUME0, &vlf);
190         mMixer->setParameter(index, AudioMixer::VOLUME, AudioMixer::VOLUME1, &vrf);
191 
192         mMixer->setParameter(index, AudioMixer::RESAMPLE, AudioMixer::REMOVE, nullptr);
193         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::MAIN_BUFFER,
194                 (void *)mMixerBuffer);
195         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::MIXER_FORMAT,
196                 (void *)(uintptr_t)mMixerBufferFormat);
197         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::FORMAT,
198                 (void *)(uintptr_t)fastTrack->mFormat);
199         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::CHANNEL_MASK,
200                 (void *)(uintptr_t)fastTrack->mChannelMask);
201         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::MIXER_CHANNEL_MASK,
202                 (void *)(uintptr_t)mSinkChannelMask);
203         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::HAPTIC_ENABLED,
204                 (void *)(uintptr_t)fastTrack->mHapticPlaybackEnabled);
205         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::HAPTIC_INTENSITY,
206                 (void *)(uintptr_t)fastTrack->mHapticIntensity);
207 
208         mMixer->enable(index);
209         break;
210     default:
211         LOG_ALWAYS_FATAL("%s: invalid update reason %d", __func__, reason);
212     }
213 }
214 
onStateChange()215 void FastMixer::onStateChange()
216 {
217     const FastMixerState * const current = (const FastMixerState *) mCurrent;
218     const FastMixerState * const previous = (const FastMixerState *) mPrevious;
219     FastMixerDumpState * const dumpState = (FastMixerDumpState *) mDumpState;
220     const size_t frameCount = current->mFrameCount;
221 
222     // update boottime offset, in case it has changed
223     mTimestamp.mTimebaseOffset[ExtendedTimestamp::TIMEBASE_BOOTTIME] =
224             mBoottimeOffset.load();
225 
226     // handle state change here, but since we want to diff the state,
227     // we're prepared for previous == &sInitial the first time through
228     unsigned previousTrackMask;
229 
230     // check for change in output HAL configuration
231     NBAIO_Format previousFormat = mFormat;
232     if (current->mOutputSinkGen != mOutputSinkGen) {
233         mOutputSink = current->mOutputSink;
234         mOutputSinkGen = current->mOutputSinkGen;
235         mSinkChannelMask = current->mSinkChannelMask;
236         mBalance.setChannelMask(mSinkChannelMask);
237         if (mOutputSink == NULL) {
238             mFormat = Format_Invalid;
239             mSampleRate = 0;
240             mSinkChannelCount = 0;
241             mSinkChannelMask = AUDIO_CHANNEL_NONE;
242             mAudioChannelCount = 0;
243         } else {
244             mFormat = mOutputSink->format();
245             mSampleRate = Format_sampleRate(mFormat);
246             mSinkChannelCount = Format_channelCount(mFormat);
247             LOG_ALWAYS_FATAL_IF(mSinkChannelCount > AudioMixer::MAX_NUM_CHANNELS);
248 
249             if (mSinkChannelMask == AUDIO_CHANNEL_NONE) {
250                 mSinkChannelMask = getChannelMaskFromCount(mSinkChannelCount);
251             }
252             mAudioChannelCount = mSinkChannelCount - audio_channel_count_from_out_mask(
253                     mSinkChannelMask & AUDIO_CHANNEL_HAPTIC_ALL);
254         }
255         dumpState->mSampleRate = mSampleRate;
256     }
257 
258     if ((!Format_isEqual(mFormat, previousFormat)) || (frameCount != previous->mFrameCount)) {
259         // FIXME to avoid priority inversion, don't delete here
260         delete mMixer;
261         mMixer = NULL;
262         free(mMixerBuffer);
263         mMixerBuffer = NULL;
264         free(mSinkBuffer);
265         mSinkBuffer = NULL;
266         if (frameCount > 0 && mSampleRate > 0) {
267             // FIXME new may block for unbounded time at internal mutex of the heap
268             //       implementation; it would be better to have normal mixer allocate for us
269             //       to avoid blocking here and to prevent possible priority inversion
270             mMixer = new AudioMixer(frameCount, mSampleRate);
271             // FIXME See the other FIXME at FastMixer::setNBLogWriter()
272             NBLog::thread_params_t params;
273             params.frameCount = frameCount;
274             params.sampleRate = mSampleRate;
275             LOG_THREAD_PARAMS(params);
276             const size_t mixerFrameSize = mSinkChannelCount
277                     * audio_bytes_per_sample(mMixerBufferFormat);
278             mMixerBufferSize = mixerFrameSize * frameCount;
279             (void)posix_memalign(&mMixerBuffer, 32, mMixerBufferSize);
280             const size_t sinkFrameSize = mSinkChannelCount
281                     * audio_bytes_per_sample(mFormat.mFormat);
282             if (sinkFrameSize > mixerFrameSize) { // need a sink buffer
283                 mSinkBufferSize = sinkFrameSize * frameCount;
284                 (void)posix_memalign(&mSinkBuffer, 32, mSinkBufferSize);
285             }
286             mPeriodNs = (frameCount * 1000000000LL) / mSampleRate;    // 1.00
287             mUnderrunNs = (frameCount * 1750000000LL) / mSampleRate;  // 1.75
288             mOverrunNs = (frameCount * 500000000LL) / mSampleRate;    // 0.50
289             mForceNs = (frameCount * 950000000LL) / mSampleRate;      // 0.95
290             mWarmupNsMin = (frameCount * 750000000LL) / mSampleRate;  // 0.75
291             mWarmupNsMax = (frameCount * 1250000000LL) / mSampleRate; // 1.25
292         } else {
293             mPeriodNs = 0;
294             mUnderrunNs = 0;
295             mOverrunNs = 0;
296             mForceNs = 0;
297             mWarmupNsMin = 0;
298             mWarmupNsMax = LONG_MAX;
299         }
300         mMixerBufferState = UNDEFINED;
301         // we need to reconfigure all active tracks
302         previousTrackMask = 0;
303         mFastTracksGen = current->mFastTracksGen - 1;
304         dumpState->mFrameCount = frameCount;
305 #ifdef TEE_SINK
306         mTee.set(mFormat, NBAIO_Tee::TEE_FLAG_OUTPUT_THREAD);
307         mTee.setId(std::string("_") + std::to_string(mThreadIoHandle) + "_F");
308 #endif
309     } else {
310         previousTrackMask = previous->mTrackMask;
311     }
312 
313     // check for change in active track set
314     const unsigned currentTrackMask = current->mTrackMask;
315     dumpState->mTrackMask = currentTrackMask;
316     dumpState->mNumTracks = popcount(currentTrackMask);
317     if (current->mFastTracksGen != mFastTracksGen) {
318 
319         // process removed tracks first to avoid running out of track names
320         unsigned removedTracks = previousTrackMask & ~currentTrackMask;
321         while (removedTracks != 0) {
322             int i = __builtin_ctz(removedTracks);
323             removedTracks &= ~(1 << i);
324             updateMixerTrack(i, REASON_REMOVE);
325             // don't reset track dump state, since other side is ignoring it
326         }
327 
328         // now process added tracks
329         unsigned addedTracks = currentTrackMask & ~previousTrackMask;
330         while (addedTracks != 0) {
331             int i = __builtin_ctz(addedTracks);
332             addedTracks &= ~(1 << i);
333             updateMixerTrack(i, REASON_ADD);
334         }
335 
336         // finally process (potentially) modified tracks; these use the same slot
337         // but may have a different buffer provider or volume provider
338         unsigned modifiedTracks = currentTrackMask & previousTrackMask;
339         while (modifiedTracks != 0) {
340             int i = __builtin_ctz(modifiedTracks);
341             modifiedTracks &= ~(1 << i);
342             updateMixerTrack(i, REASON_MODIFY);
343         }
344 
345         mFastTracksGen = current->mFastTracksGen;
346     }
347 }
348 
onWork()349 void FastMixer::onWork()
350 {
351     // TODO: pass an ID parameter to indicate which time series we want to write to in NBLog.cpp
352     // Or: pass both of these into a single call with a boolean
353     const FastMixerState * const current = (const FastMixerState *) mCurrent;
354     FastMixerDumpState * const dumpState = (FastMixerDumpState *) mDumpState;
355 
356     if (mIsWarm) {
357         // Logging timestamps for FastMixer is currently disabled to make memory room for logging
358         // other statistics in FastMixer.
359         // To re-enable, delete the #ifdef FASTMIXER_LOG_HIST_TS lines (and the #endif lines).
360 #ifdef FASTMIXER_LOG_HIST_TS
361         LOG_HIST_TS();
362 #endif
363         //ALOGD("Eric FastMixer::onWork() mIsWarm");
364     } else {
365         dumpState->mTimestampVerifier.discontinuity(
366             dumpState->mTimestampVerifier.DISCONTINUITY_MODE_CONTINUOUS);
367         // See comment in if block.
368 #ifdef FASTMIXER_LOG_HIST_TS
369         LOG_AUDIO_STATE();
370 #endif
371     }
372     const FastMixerState::Command command = mCommand;
373     const size_t frameCount = current->mFrameCount;
374 
375     if ((command & FastMixerState::MIX) && (mMixer != NULL) && mIsWarm) {
376         ALOG_ASSERT(mMixerBuffer != NULL);
377 
378         // AudioMixer::mState.enabledTracks is undefined if mState.hook == process__validate,
379         // so we keep a side copy of enabledTracks
380         bool anyEnabledTracks = false;
381 
382         // for each track, update volume and check for underrun
383         unsigned currentTrackMask = current->mTrackMask;
384         while (currentTrackMask != 0) {
385             int i = __builtin_ctz(currentTrackMask);
386             currentTrackMask &= ~(1 << i);
387             const FastTrack* fastTrack = &current->mFastTracks[i];
388 
389             const int64_t trackFramesWrittenButNotPresented =
390                 mNativeFramesWrittenButNotPresented;
391             const int64_t trackFramesWritten = fastTrack->mBufferProvider->framesReleased();
392             ExtendedTimestamp perTrackTimestamp(mTimestamp);
393 
394             // Can't provide an ExtendedTimestamp before first frame presented.
395             // Also, timestamp may not go to very last frame on stop().
396             if (trackFramesWritten >= trackFramesWrittenButNotPresented &&
397                     perTrackTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] > 0) {
398                 perTrackTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] =
399                         trackFramesWritten - trackFramesWrittenButNotPresented;
400             } else {
401                 perTrackTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] = 0;
402                 perTrackTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] = -1;
403             }
404             perTrackTimestamp.mPosition[ExtendedTimestamp::LOCATION_SERVER] = trackFramesWritten;
405             fastTrack->mBufferProvider->onTimestamp(perTrackTimestamp);
406 
407             const int name = i;
408             if (fastTrack->mVolumeProvider != NULL) {
409                 gain_minifloat_packed_t vlr = fastTrack->mVolumeProvider->getVolumeLR();
410                 float vlf = float_from_gain(gain_minifloat_unpack_left(vlr));
411                 float vrf = float_from_gain(gain_minifloat_unpack_right(vlr));
412 
413                 mMixer->setParameter(name, AudioMixer::RAMP_VOLUME, AudioMixer::VOLUME0, &vlf);
414                 mMixer->setParameter(name, AudioMixer::RAMP_VOLUME, AudioMixer::VOLUME1, &vrf);
415             }
416             // FIXME The current implementation of framesReady() for fast tracks
417             // takes a tryLock, which can block
418             // up to 1 ms.  If enough active tracks all blocked in sequence, this would result
419             // in the overall fast mix cycle being delayed.  Should use a non-blocking FIFO.
420             size_t framesReady = fastTrack->mBufferProvider->framesReady();
421             if (ATRACE_ENABLED()) {
422                 // I wish we had formatted trace names
423                 char traceName[16];
424                 strcpy(traceName, "fRdy");
425                 traceName[4] = i + (i < 10 ? '0' : 'A' - 10);
426                 traceName[5] = '\0';
427                 ATRACE_INT(traceName, framesReady);
428             }
429             FastTrackDump *ftDump = &dumpState->mTracks[i];
430             FastTrackUnderruns underruns = ftDump->mUnderruns;
431             if (framesReady < frameCount) {
432                 if (framesReady == 0) {
433                     underruns.mBitFields.mEmpty++;
434                     underruns.mBitFields.mMostRecent = UNDERRUN_EMPTY;
435                     mMixer->disable(name);
436                 } else {
437                     // allow mixing partial buffer
438                     underruns.mBitFields.mPartial++;
439                     underruns.mBitFields.mMostRecent = UNDERRUN_PARTIAL;
440                     mMixer->enable(name);
441                     anyEnabledTracks = true;
442                 }
443             } else {
444                 underruns.mBitFields.mFull++;
445                 underruns.mBitFields.mMostRecent = UNDERRUN_FULL;
446                 mMixer->enable(name);
447                 anyEnabledTracks = true;
448             }
449             ftDump->mUnderruns = underruns;
450             ftDump->mFramesReady = framesReady;
451             ftDump->mFramesWritten = trackFramesWritten;
452         }
453 
454         if (anyEnabledTracks) {
455             // process() is CPU-bound
456             mMixer->process();
457             mMixerBufferState = MIXED;
458         } else if (mMixerBufferState != ZEROED) {
459             mMixerBufferState = UNDEFINED;
460         }
461 
462     } else if (mMixerBufferState == MIXED) {
463         mMixerBufferState = UNDEFINED;
464     }
465     //bool didFullWrite = false;    // dumpsys could display a count of partial writes
466     if ((command & FastMixerState::WRITE) && (mOutputSink != NULL) && (mMixerBuffer != NULL)) {
467         if (mMixerBufferState == UNDEFINED) {
468             memset(mMixerBuffer, 0, mMixerBufferSize);
469             mMixerBufferState = ZEROED;
470         }
471 
472         if (mMasterMono.load()) {  // memory_order_seq_cst
473             mono_blend(mMixerBuffer, mMixerBufferFormat, Format_channelCount(mFormat), frameCount,
474                     true /*limit*/);
475         }
476 
477         // Balance must take effect after mono conversion.
478         // mBalance detects zero balance within the class for speed (not needed here).
479         mBalance.setBalance(mMasterBalance.load());
480         mBalance.process((float *)mMixerBuffer, frameCount);
481 
482         // prepare the buffer used to write to sink
483         void *buffer = mSinkBuffer != NULL ? mSinkBuffer : mMixerBuffer;
484         if (mFormat.mFormat != mMixerBufferFormat) { // sink format not the same as mixer format
485             memcpy_by_audio_format(buffer, mFormat.mFormat, mMixerBuffer, mMixerBufferFormat,
486                     frameCount * Format_channelCount(mFormat));
487         }
488         if (mSinkChannelMask & AUDIO_CHANNEL_HAPTIC_ALL) {
489             // When there are haptic channels, the sample data is partially interleaved.
490             // Make the sample data fully interleaved here.
491             adjust_channels_non_destructive(buffer, mAudioChannelCount, buffer, mSinkChannelCount,
492                     audio_bytes_per_sample(mFormat.mFormat),
493                     frameCount * audio_bytes_per_frame(mAudioChannelCount, mFormat.mFormat));
494         }
495         // if non-NULL, then duplicate write() to this non-blocking sink
496 #ifdef TEE_SINK
497         mTee.write(buffer, frameCount);
498 #endif
499         // FIXME write() is non-blocking and lock-free for a properly implemented NBAIO sink,
500         //       but this code should be modified to handle both non-blocking and blocking sinks
501         dumpState->mWriteSequence++;
502         ATRACE_BEGIN("write");
503         ssize_t framesWritten = mOutputSink->write(buffer, frameCount);
504         ATRACE_END();
505         dumpState->mWriteSequence++;
506         if (framesWritten >= 0) {
507             ALOG_ASSERT((size_t) framesWritten <= frameCount);
508             mTotalNativeFramesWritten += framesWritten;
509             dumpState->mFramesWritten = mTotalNativeFramesWritten;
510             //if ((size_t) framesWritten == frameCount) {
511             //    didFullWrite = true;
512             //}
513         } else {
514             dumpState->mWriteErrors++;
515         }
516         mAttemptedWrite = true;
517         // FIXME count # of writes blocked excessively, CPU usage, etc. for dump
518 
519         if (mIsWarm) {
520             ExtendedTimestamp timestamp; // local
521             status_t status = mOutputSink->getTimestamp(timestamp);
522             if (status == NO_ERROR) {
523                 dumpState->mTimestampVerifier.add(
524                         timestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL],
525                         timestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL],
526                         mSampleRate);
527                 const int64_t totalNativeFramesPresented =
528                         timestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL];
529                 if (totalNativeFramesPresented <= mTotalNativeFramesWritten) {
530                     mNativeFramesWrittenButNotPresented =
531                         mTotalNativeFramesWritten - totalNativeFramesPresented;
532                     mTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] =
533                             timestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL];
534                     mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] =
535                             timestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL];
536                     // We don't compensate for server - kernel time difference and
537                     // only update latency if we have valid info.
538                     const double latencyMs =
539                             (double)mNativeFramesWrittenButNotPresented * 1000 / mSampleRate;
540                     dumpState->mLatencyMs = latencyMs;
541                     LOG_LATENCY(latencyMs);
542                 } else {
543                     // HAL reported that more frames were presented than were written
544                     mNativeFramesWrittenButNotPresented = 0;
545                     status = INVALID_OPERATION;
546                 }
547             } else {
548                 dumpState->mTimestampVerifier.error();
549             }
550             if (status == NO_ERROR) {
551                 mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_SERVER] =
552                         mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL];
553             } else {
554                 // fetch server time if we can't get timestamp
555                 mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_SERVER] =
556                         systemTime(SYSTEM_TIME_MONOTONIC);
557                 // clear out kernel cached position as this may get rapidly stale
558                 // if we never get a new valid timestamp
559                 mTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] = 0;
560                 mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] = -1;
561             }
562         }
563     }
564 }
565 
566 }   // namespace android
567