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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     // FIXME pass sInitial as parameter to base class constructor, and make it static local
83     mPrevious = &sInitial;
84     mCurrent = &sInitial;
85 
86     mDummyDumpState = &mDummyFastMixerDumpState;
87     // TODO: Add channel mask to NBAIO_Format.
88     // We assume that the channel mask must be a valid positional channel mask.
89     mSinkChannelMask = getChannelMaskFromCount(mSinkChannelCount);
90     mBalance.setChannelMask(mSinkChannelMask);
91 
92     unsigned i;
93     for (i = 0; i < FastMixerState::sMaxFastTracks; ++i) {
94         mGenerations[i] = 0;
95     }
96 #ifdef FAST_THREAD_STATISTICS
97     mOldLoad.tv_sec = 0;
98     mOldLoad.tv_nsec = 0;
99 #endif
100 }
101 
~FastMixer()102 FastMixer::~FastMixer()
103 {
104 }
105 
sq()106 FastMixerStateQueue* FastMixer::sq()
107 {
108     return &mSQ;
109 }
110 
poll()111 const FastThreadState *FastMixer::poll()
112 {
113     return mSQ.poll();
114 }
115 
setNBLogWriter(NBLog::Writer * logWriter __unused)116 void FastMixer::setNBLogWriter(NBLog::Writer *logWriter __unused)
117 {
118 }
119 
onIdle()120 void FastMixer::onIdle()
121 {
122     mPreIdle = *(const FastMixerState *)mCurrent;
123     mCurrent = &mPreIdle;
124 }
125 
onExit()126 void FastMixer::onExit()
127 {
128     delete mMixer;
129     free(mMixerBuffer);
130     free(mSinkBuffer);
131 }
132 
isSubClassCommand(FastThreadState::Command command)133 bool FastMixer::isSubClassCommand(FastThreadState::Command command)
134 {
135     switch ((FastMixerState::Command) command) {
136     case FastMixerState::MIX:
137     case FastMixerState::WRITE:
138     case FastMixerState::MIX_WRITE:
139         return true;
140     default:
141         return false;
142     }
143 }
144 
updateMixerTrack(int index,Reason reason)145 void FastMixer::updateMixerTrack(int index, Reason reason) {
146     const FastMixerState * const current = (const FastMixerState *) mCurrent;
147     const FastTrack * const fastTrack = &current->mFastTracks[index];
148 
149     // check and update generation
150     if (reason == REASON_MODIFY && mGenerations[index] == fastTrack->mGeneration) {
151         return; // no change on an already configured track.
152     }
153     mGenerations[index] = fastTrack->mGeneration;
154 
155     // mMixer == nullptr on configuration failure (check done after generation update).
156     if (mMixer == nullptr) {
157         return;
158     }
159 
160     switch (reason) {
161     case REASON_REMOVE:
162         mMixer->destroy(index);
163         break;
164     case REASON_ADD: {
165         const status_t status = mMixer->create(
166                 index, fastTrack->mChannelMask, fastTrack->mFormat, AUDIO_SESSION_OUTPUT_MIX);
167         LOG_ALWAYS_FATAL_IF(status != NO_ERROR,
168                 "%s: cannot create fast track index"
169                 " %d, mask %#x, format %#x in AudioMixer",
170                 __func__, index, fastTrack->mChannelMask, fastTrack->mFormat);
171     }
172         [[fallthrough]];  // now fallthrough to update the newly created track.
173     case REASON_MODIFY:
174         mMixer->setBufferProvider(index, fastTrack->mBufferProvider);
175 
176         float vlf, vrf;
177         if (fastTrack->mVolumeProvider != nullptr) {
178             const gain_minifloat_packed_t vlr = fastTrack->mVolumeProvider->getVolumeLR();
179             vlf = float_from_gain(gain_minifloat_unpack_left(vlr));
180             vrf = float_from_gain(gain_minifloat_unpack_right(vlr));
181         } else {
182             vlf = vrf = AudioMixer::UNITY_GAIN_FLOAT;
183         }
184 
185         // set volume to avoid ramp whenever the track is updated (or created).
186         // Note: this does not distinguish from starting fresh or
187         // resuming from a paused state.
188         mMixer->setParameter(index, AudioMixer::VOLUME, AudioMixer::VOLUME0, &vlf);
189         mMixer->setParameter(index, AudioMixer::VOLUME, AudioMixer::VOLUME1, &vrf);
190 
191         mMixer->setParameter(index, AudioMixer::RESAMPLE, AudioMixer::REMOVE, nullptr);
192         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::MAIN_BUFFER,
193                 (void *)mMixerBuffer);
194         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::MIXER_FORMAT,
195                 (void *)(uintptr_t)mMixerBufferFormat);
196         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::FORMAT,
197                 (void *)(uintptr_t)fastTrack->mFormat);
198         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::CHANNEL_MASK,
199                 (void *)(uintptr_t)fastTrack->mChannelMask);
200         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::MIXER_CHANNEL_MASK,
201                 (void *)(uintptr_t)mSinkChannelMask);
202         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::HAPTIC_ENABLED,
203                 (void *)(uintptr_t)fastTrack->mHapticPlaybackEnabled);
204         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::HAPTIC_INTENSITY,
205                 (void *)(uintptr_t)fastTrack->mHapticIntensity);
206         mMixer->setParameter(index, AudioMixer::TRACK, AudioMixer::HAPTIC_MAX_AMPLITUDE,
207                 (void *)(&(fastTrack->mHapticMaxAmplitude)));
208 
209         mMixer->enable(index);
210         break;
211     default:
212         LOG_ALWAYS_FATAL("%s: invalid update reason %d", __func__, reason);
213     }
214 }
215 
onStateChange()216 void FastMixer::onStateChange()
217 {
218     const FastMixerState * const current = (const FastMixerState *) mCurrent;
219     const FastMixerState * const previous = (const FastMixerState *) mPrevious;
220     FastMixerDumpState * const dumpState = (FastMixerDumpState *) mDumpState;
221     const size_t frameCount = current->mFrameCount;
222 
223     // update boottime offset, in case it has changed
224     mTimestamp.mTimebaseOffset[ExtendedTimestamp::TIMEBASE_BOOTTIME] =
225             mBoottimeOffset.load();
226 
227     // handle state change here, but since we want to diff the state,
228     // we're prepared for previous == &sInitial the first time through
229     unsigned previousTrackMask;
230 
231     // check for change in output HAL configuration
232     NBAIO_Format previousFormat = mFormat;
233     if (current->mOutputSinkGen != mOutputSinkGen) {
234         mOutputSink = current->mOutputSink;
235         mOutputSinkGen = current->mOutputSinkGen;
236         mSinkChannelMask = current->mSinkChannelMask;
237         mBalance.setChannelMask(mSinkChannelMask);
238         if (mOutputSink == NULL) {
239             mFormat = Format_Invalid;
240             mSampleRate = 0;
241             mSinkChannelCount = 0;
242             mSinkChannelMask = AUDIO_CHANNEL_NONE;
243             mAudioChannelCount = 0;
244         } else {
245             mFormat = mOutputSink->format();
246             mSampleRate = Format_sampleRate(mFormat);
247             mSinkChannelCount = Format_channelCount(mFormat);
248             LOG_ALWAYS_FATAL_IF(mSinkChannelCount > AudioMixer::MAX_NUM_CHANNELS);
249 
250             if (mSinkChannelMask == AUDIO_CHANNEL_NONE) {
251                 mSinkChannelMask = getChannelMaskFromCount(mSinkChannelCount);
252             }
253             mAudioChannelCount = mSinkChannelCount - audio_channel_count_from_out_mask(
254                     mSinkChannelMask & AUDIO_CHANNEL_HAPTIC_ALL);
255         }
256         dumpState->mSampleRate = mSampleRate;
257     }
258 
259     if ((!Format_isEqual(mFormat, previousFormat)) || (frameCount != previous->mFrameCount)) {
260         // FIXME to avoid priority inversion, don't delete here
261         delete mMixer;
262         mMixer = NULL;
263         free(mMixerBuffer);
264         mMixerBuffer = NULL;
265         free(mSinkBuffer);
266         mSinkBuffer = NULL;
267         if (frameCount > 0 && mSampleRate > 0) {
268             // FIXME new may block for unbounded time at internal mutex of the heap
269             //       implementation; it would be better to have normal mixer allocate for us
270             //       to avoid blocking here and to prevent possible priority inversion
271             mMixer = new AudioMixer(frameCount, mSampleRate);
272             // FIXME See the other FIXME at FastMixer::setNBLogWriter()
273             NBLog::thread_params_t params;
274             params.frameCount = frameCount;
275             params.sampleRate = mSampleRate;
276             LOG_THREAD_PARAMS(params);
277             const size_t mixerFrameSize = mSinkChannelCount
278                     * audio_bytes_per_sample(mMixerBufferFormat);
279             mMixerBufferSize = mixerFrameSize * frameCount;
280             (void)posix_memalign(&mMixerBuffer, 32, mMixerBufferSize);
281             const size_t sinkFrameSize = mSinkChannelCount
282                     * audio_bytes_per_sample(mFormat.mFormat);
283             if (sinkFrameSize > mixerFrameSize) { // need a sink buffer
284                 mSinkBufferSize = sinkFrameSize * frameCount;
285                 (void)posix_memalign(&mSinkBuffer, 32, mSinkBufferSize);
286             }
287             mPeriodNs = (frameCount * 1000000000LL) / mSampleRate;    // 1.00
288             mUnderrunNs = (frameCount * 1750000000LL) / mSampleRate;  // 1.75
289             mOverrunNs = (frameCount * 500000000LL) / mSampleRate;    // 0.50
290             mForceNs = (frameCount * 950000000LL) / mSampleRate;      // 0.95
291             mWarmupNsMin = (frameCount * 750000000LL) / mSampleRate;  // 0.75
292             mWarmupNsMax = (frameCount * 1250000000LL) / mSampleRate; // 1.25
293         } else {
294             mPeriodNs = 0;
295             mUnderrunNs = 0;
296             mOverrunNs = 0;
297             mForceNs = 0;
298             mWarmupNsMin = 0;
299             mWarmupNsMax = LONG_MAX;
300         }
301         mMixerBufferState = UNDEFINED;
302         // we need to reconfigure all active tracks
303         previousTrackMask = 0;
304         mFastTracksGen = current->mFastTracksGen - 1;
305         dumpState->mFrameCount = frameCount;
306 #ifdef TEE_SINK
307         mTee.set(mFormat, NBAIO_Tee::TEE_FLAG_OUTPUT_THREAD);
308         mTee.setId(std::string("_") + std::to_string(mThreadIoHandle) + "_F");
309 #endif
310     } else {
311         previousTrackMask = previous->mTrackMask;
312     }
313 
314     // check for change in active track set
315     const unsigned currentTrackMask = current->mTrackMask;
316     dumpState->mTrackMask = currentTrackMask;
317     dumpState->mNumTracks = popcount(currentTrackMask);
318     if (current->mFastTracksGen != mFastTracksGen) {
319 
320         // process removed tracks first to avoid running out of track names
321         unsigned removedTracks = previousTrackMask & ~currentTrackMask;
322         while (removedTracks != 0) {
323             int i = __builtin_ctz(removedTracks);
324             removedTracks &= ~(1 << i);
325             updateMixerTrack(i, REASON_REMOVE);
326             // don't reset track dump state, since other side is ignoring it
327         }
328 
329         // now process added tracks
330         unsigned addedTracks = currentTrackMask & ~previousTrackMask;
331         while (addedTracks != 0) {
332             int i = __builtin_ctz(addedTracks);
333             addedTracks &= ~(1 << i);
334             updateMixerTrack(i, REASON_ADD);
335         }
336 
337         // finally process (potentially) modified tracks; these use the same slot
338         // but may have a different buffer provider or volume provider
339         unsigned modifiedTracks = currentTrackMask & previousTrackMask;
340         while (modifiedTracks != 0) {
341             int i = __builtin_ctz(modifiedTracks);
342             modifiedTracks &= ~(1 << i);
343             updateMixerTrack(i, REASON_MODIFY);
344         }
345 
346         mFastTracksGen = current->mFastTracksGen;
347     }
348 }
349 
onWork()350 void FastMixer::onWork()
351 {
352     // TODO: pass an ID parameter to indicate which time series we want to write to in NBLog.cpp
353     // Or: pass both of these into a single call with a boolean
354     const FastMixerState * const current = (const FastMixerState *) mCurrent;
355     FastMixerDumpState * const dumpState = (FastMixerDumpState *) mDumpState;
356 
357     if (mIsWarm) {
358         // Logging timestamps for FastMixer is currently disabled to make memory room for logging
359         // other statistics in FastMixer.
360         // To re-enable, delete the #ifdef FASTMIXER_LOG_HIST_TS lines (and the #endif lines).
361 #ifdef FASTMIXER_LOG_HIST_TS
362         LOG_HIST_TS();
363 #endif
364         //ALOGD("Eric FastMixer::onWork() mIsWarm");
365     } else {
366         dumpState->mTimestampVerifier.discontinuity(
367             dumpState->mTimestampVerifier.DISCONTINUITY_MODE_CONTINUOUS);
368         // See comment in if block.
369 #ifdef FASTMIXER_LOG_HIST_TS
370         LOG_AUDIO_STATE();
371 #endif
372     }
373     const FastMixerState::Command command = mCommand;
374     const size_t frameCount = current->mFrameCount;
375 
376     if ((command & FastMixerState::MIX) && (mMixer != NULL) && mIsWarm) {
377         ALOG_ASSERT(mMixerBuffer != NULL);
378 
379         // AudioMixer::mState.enabledTracks is undefined if mState.hook == process__validate,
380         // so we keep a side copy of enabledTracks
381         bool anyEnabledTracks = false;
382 
383         // for each track, update volume and check for underrun
384         unsigned currentTrackMask = current->mTrackMask;
385         while (currentTrackMask != 0) {
386             int i = __builtin_ctz(currentTrackMask);
387             currentTrackMask &= ~(1 << i);
388             const FastTrack* fastTrack = &current->mFastTracks[i];
389 
390             const int64_t trackFramesWrittenButNotPresented =
391                 mNativeFramesWrittenButNotPresented;
392             const int64_t trackFramesWritten = fastTrack->mBufferProvider->framesReleased();
393             ExtendedTimestamp perTrackTimestamp(mTimestamp);
394 
395             // Can't provide an ExtendedTimestamp before first frame presented.
396             // Also, timestamp may not go to very last frame on stop().
397             if (trackFramesWritten >= trackFramesWrittenButNotPresented &&
398                     perTrackTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] > 0) {
399                 perTrackTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] =
400                         trackFramesWritten - trackFramesWrittenButNotPresented;
401             } else {
402                 perTrackTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] = 0;
403                 perTrackTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] = -1;
404             }
405             perTrackTimestamp.mPosition[ExtendedTimestamp::LOCATION_SERVER] = trackFramesWritten;
406             fastTrack->mBufferProvider->onTimestamp(perTrackTimestamp);
407 
408             const int name = i;
409             if (fastTrack->mVolumeProvider != NULL) {
410                 gain_minifloat_packed_t vlr = fastTrack->mVolumeProvider->getVolumeLR();
411                 float vlf = float_from_gain(gain_minifloat_unpack_left(vlr));
412                 float vrf = float_from_gain(gain_minifloat_unpack_right(vlr));
413 
414                 mMixer->setParameter(name, AudioMixer::RAMP_VOLUME, AudioMixer::VOLUME0, &vlf);
415                 mMixer->setParameter(name, AudioMixer::RAMP_VOLUME, AudioMixer::VOLUME1, &vrf);
416             }
417             // FIXME The current implementation of framesReady() for fast tracks
418             // takes a tryLock, which can block
419             // up to 1 ms.  If enough active tracks all blocked in sequence, this would result
420             // in the overall fast mix cycle being delayed.  Should use a non-blocking FIFO.
421             size_t framesReady = fastTrack->mBufferProvider->framesReady();
422             if (ATRACE_ENABLED()) {
423                 // I wish we had formatted trace names
424                 char traceName[16];
425                 strcpy(traceName, "fRdy");
426                 traceName[4] = i + (i < 10 ? '0' : 'A' - 10);
427                 traceName[5] = '\0';
428                 ATRACE_INT(traceName, framesReady);
429             }
430             FastTrackDump *ftDump = &dumpState->mTracks[i];
431             FastTrackUnderruns underruns = ftDump->mUnderruns;
432             if (framesReady < frameCount) {
433                 if (framesReady == 0) {
434                     underruns.mBitFields.mEmpty++;
435                     underruns.mBitFields.mMostRecent = UNDERRUN_EMPTY;
436                     mMixer->disable(name);
437                 } else {
438                     // allow mixing partial buffer
439                     underruns.mBitFields.mPartial++;
440                     underruns.mBitFields.mMostRecent = UNDERRUN_PARTIAL;
441                     mMixer->enable(name);
442                     anyEnabledTracks = true;
443                 }
444             } else {
445                 underruns.mBitFields.mFull++;
446                 underruns.mBitFields.mMostRecent = UNDERRUN_FULL;
447                 mMixer->enable(name);
448                 anyEnabledTracks = true;
449             }
450             ftDump->mUnderruns = underruns;
451             ftDump->mFramesReady = framesReady;
452             ftDump->mFramesWritten = trackFramesWritten;
453         }
454 
455         if (anyEnabledTracks) {
456             // process() is CPU-bound
457             mMixer->process();
458             mMixerBufferState = MIXED;
459         } else if (mMixerBufferState != ZEROED) {
460             mMixerBufferState = UNDEFINED;
461         }
462 
463     } else if (mMixerBufferState == MIXED) {
464         mMixerBufferState = UNDEFINED;
465     }
466     //bool didFullWrite = false;    // dumpsys could display a count of partial writes
467     if ((command & FastMixerState::WRITE) && (mOutputSink != NULL) && (mMixerBuffer != NULL)) {
468         if (mMixerBufferState == UNDEFINED) {
469             memset(mMixerBuffer, 0, mMixerBufferSize);
470             mMixerBufferState = ZEROED;
471         }
472 
473         if (mMasterMono.load()) {  // memory_order_seq_cst
474             mono_blend(mMixerBuffer, mMixerBufferFormat, Format_channelCount(mFormat), frameCount,
475                     true /*limit*/);
476         }
477 
478         // Balance must take effect after mono conversion.
479         // mBalance detects zero balance within the class for speed (not needed here).
480         mBalance.setBalance(mMasterBalance.load());
481         mBalance.process((float *)mMixerBuffer, frameCount);
482 
483         // prepare the buffer used to write to sink
484         void *buffer = mSinkBuffer != NULL ? mSinkBuffer : mMixerBuffer;
485         if (mFormat.mFormat != mMixerBufferFormat) { // sink format not the same as mixer format
486             memcpy_by_audio_format(buffer, mFormat.mFormat, mMixerBuffer, mMixerBufferFormat,
487                     frameCount * Format_channelCount(mFormat));
488         }
489         if (mSinkChannelMask & AUDIO_CHANNEL_HAPTIC_ALL) {
490             // When there are haptic channels, the sample data is partially interleaved.
491             // Make the sample data fully interleaved here.
492             adjust_channels_non_destructive(buffer, mAudioChannelCount, buffer, mSinkChannelCount,
493                     audio_bytes_per_sample(mFormat.mFormat),
494                     frameCount * audio_bytes_per_frame(mAudioChannelCount, mFormat.mFormat));
495         }
496         // if non-NULL, then duplicate write() to this non-blocking sink
497 #ifdef TEE_SINK
498         mTee.write(buffer, frameCount);
499 #endif
500         // FIXME write() is non-blocking and lock-free for a properly implemented NBAIO sink,
501         //       but this code should be modified to handle both non-blocking and blocking sinks
502         dumpState->mWriteSequence++;
503         ATRACE_BEGIN("write");
504         ssize_t framesWritten = mOutputSink->write(buffer, frameCount);
505         ATRACE_END();
506         dumpState->mWriteSequence++;
507         if (framesWritten >= 0) {
508             ALOG_ASSERT((size_t) framesWritten <= frameCount);
509             mTotalNativeFramesWritten += framesWritten;
510             dumpState->mFramesWritten = mTotalNativeFramesWritten;
511             //if ((size_t) framesWritten == frameCount) {
512             //    didFullWrite = true;
513             //}
514         } else {
515             dumpState->mWriteErrors++;
516         }
517         mAttemptedWrite = true;
518         // FIXME count # of writes blocked excessively, CPU usage, etc. for dump
519 
520         if (mIsWarm) {
521             ExtendedTimestamp timestamp; // local
522             status_t status = mOutputSink->getTimestamp(timestamp);
523             if (status == NO_ERROR) {
524                 dumpState->mTimestampVerifier.add(
525                         timestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL],
526                         timestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL],
527                         mSampleRate);
528                 const int64_t totalNativeFramesPresented =
529                         timestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL];
530                 if (totalNativeFramesPresented <= mTotalNativeFramesWritten) {
531                     mNativeFramesWrittenButNotPresented =
532                         mTotalNativeFramesWritten - totalNativeFramesPresented;
533                     mTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] =
534                             timestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL];
535                     mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] =
536                             timestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL];
537                     // We don't compensate for server - kernel time difference and
538                     // only update latency if we have valid info.
539                     const double latencyMs =
540                             (double)mNativeFramesWrittenButNotPresented * 1000 / mSampleRate;
541                     dumpState->mLatencyMs = latencyMs;
542                     LOG_LATENCY(latencyMs);
543                 } else {
544                     // HAL reported that more frames were presented than were written
545                     mNativeFramesWrittenButNotPresented = 0;
546                     status = INVALID_OPERATION;
547                 }
548             } else {
549                 dumpState->mTimestampVerifier.error();
550             }
551             if (status == NO_ERROR) {
552                 mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_SERVER] =
553                         mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL];
554             } else {
555                 // fetch server time if we can't get timestamp
556                 mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_SERVER] =
557                         systemTime(SYSTEM_TIME_MONOTONIC);
558                 // clear out kernel cached position as this may get rapidly stale
559                 // if we never get a new valid timestamp
560                 mTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] = 0;
561                 mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] = -1;
562             }
563         }
564     }
565 }
566 
567 }   // namespace android
568