USB audio调试
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androidstudio打印的信息有如下：
07-12 08:27:17.660 2284-2284/? I/AudioFlinger: loadHwModule() Loaded a2dp audio interface from A2DP Audio HW HAL (audio) handle 707-12 08:27:17.660 2284-2284/? I/AudioFlinger: loadHwModule() Loaded usb audio interface from USB audio HW HAL (audio) handle 807-12 08:27:17.660 2284-2284/? I/r_submix: adev_open(name=audio_hw_if)其中的第二行信息就是usb声卡的打印的一条信息。
"frameworks/av/services/audioflinger/AudioFlinger.cpp" 3024 lines --52%--1573 // loadHwModule_l() must be called with AudioFlinger::mLock held1574 audio_module_handle_t AudioFlinger::loadHwModule_l(const char *name)1575 {1576 for (size_t i = 0; i < mAudioHwDevs.size(); i++) {1577 if (strncmp(mAudioHwDevs.valueAt(i)->moduleName(), name, strlen(name)) == 0) {1578 ALOGW("loadHwModule() module %s already loaded", name);1579 return mAudioHwDevs.keyAt(i);1580 }1581 }...1643 audio_module_handle_t handle = nextUniqueId();1644 mAudioHwDevs.add(handle, new AudioHwDevice(handle, name, dev, flags));1645 1646 ALOGI("loadHwModule() Loaded %s audio interface from %s (%s) handle %d",1647 name, dev->common.module->name, dev->common.module->id, handle);1648 1649 return handle;1650 1651 }这条信息的内容是AudioFlinger打印出来的信息。调用的hardware目录下的工具。<hardware/libhardware/modules/usbaudio/audio_hal.c>1074 static struct hw_module_methods_t hal_module_methods = {1075 .open = adev_open,1076 };1077 1078 struct audio_module HAL_MODULE_INFO_SYM = {1079 .common = {1080 .tag = HARDWARE_MODULE_TAG,1081 .module_api_version = AUDIO_MODULE_API_VERSION_0_1,1082 .hal_api_version = HARDWARE_HAL_API_VERSION,1083 .id = AUDIO_HARDWARE_MODULE_ID,1084 .name = "USB audio HW HAL",1085 .author = "The Android Open Source Project",1086 .methods = &hal_module_methods,1087 },1088 };打印的信息都在common这个结构体可以找到出处。id的定义如下：
libhardware/include/hardware/audio.h:39:#define AUDIO_HARDWARE_MODULE_ID "audio"libhardware/include/hardware/audio.h:44:#define AUDIO_HARDWARE_INTERFACE "audio_hw_if"这个open函数如下：
policy文件作用：
gsc@gsc-250:/media/gsc/31269c00-69bd-4eed-814e-bade5758e213/7420_ext/frameworks$ grep -nr "AUDIO_POLICY_CONFIG_FILE"av/services/audiopolicy/managerdefault/AudioPolicyManager.cpp:2748: if (ConfigParsingUtils::loadAudioPolicyConfig(AUDIO_POLICY_CONFIG_FILE,av/services/audiopolicy/common/managerdefinitions/include/audio_policy_conf.h:26:#define AUDIO_POLICY_CONFIG_FILE "/system/etc/audio_policy.conf"
1037 static int adev_open(const hw_module_t* module, const char* name, hw_device_t** device)1038 {1039 if (strcmp(name, AUDIO_HARDWARE_INTERFACE) != 0)1040 return -EINVAL;1041 1042 struct audio_device *adev = calloc(1, sizeof(struct audio_device));1043 if (!adev)1044 return -ENOMEM;1045 1046 profile_init(&adev->out_profile, PCM_OUT);1047 profile_init(&adev->in_profile, PCM_IN);1048 1049 adev->hw_device.common.tag = HARDWARE_DEVICE_TAG;1050 adev->hw_device.common.version = AUDIO_DEVICE_API_VERSION_2_0;1051 adev->hw_device.common.module = (struct hw_module_t *)module;1052 adev->hw_device.common.close = adev_close;1053 1054 adev->hw_device.init_check = adev_init_check;1055 adev->hw_device.set_voice_volume = adev_set_voice_volume;1056 adev->hw_device.set_master_volume = adev_set_master_volume;1057 adev->hw_device.set_mode = adev_set_mode;1058 adev->hw_device.set_mic_mute = adev_set_mic_mute;1059 adev->hw_device.get_mic_mute = adev_get_mic_mute;1060 adev->hw_device.set_parameters = adev_set_parameters;1061 adev->hw_device.get_parameters = adev_get_parameters;1062 adev->hw_device.get_input_buffer_size = adev_get_input_buffer_size;1063 adev->hw_device.open_output_stream = adev_open_output_stream;1064 adev->hw_device.close_output_stream = adev_close_output_stream;1065 adev->hw_device.open_input_stream = adev_open_input_stream;1066 adev->hw_device.close_input_stream = adev_close_input_stream;1067 adev->hw_device.dump = adev_dump;1068 1069 *device = &adev->hw_device.common;1070 1071 return 0;1072 }该函数提供了其它操作硬件设备的函数。
out_profile定义于<system/media/alsa_utils/include/alsa_device_profile.h>文件。
typedef struct { int card; int device; int direction; /* PCM_OUT or PCM_IN */ enum pcm_format formats[MAX_PROFILE_FORMATS]; unsigned sample_rates[MAX_PROFILE_SAMPLE_RATES]; unsigned channel_counts[MAX_PROFILE_CHANNEL_COUNTS]; bool is_valid; /* read from the hardware device */ struct pcm_config default_config; unsigned min_period_size; unsigned max_period_size; unsigned min_channel_count; unsigned max_channel_count;} alsa_device_profile;在USB的Audio HAL层比较关键的两个函数是adev_open_output_stream和adev_open_input_stream,它们分别对应输出和输入流打开操作。
472 static int adev_open_output_stream(struct audio_hw_device *dev, 473 audio_io_handle_t handle, 474 audio_devices_t devices, 475 audio_output_flags_t flags, 476 struct audio_config *config, 477 struct audio_stream_out **stream_out, 478 const char *address /*__unused*/) 479 { 480 ALOGV("adev_open_output_stream() handle:0x%X, device:0x%X, flags:0x%X, addr:%s", 481 handle, devices, flags, address); 482 483 struct audio_device *adev = (struct audio_device *)dev; 484 485 struct stream_out *out; 486 487 out = (struct stream_out *)calloc(1, sizeof(struct stream_out)); 488 if (!out) 489 return -ENOMEM; 490 491 /* setup function pointers */ 492 out->stream.common.get_sample_rate = out_get_sample_rate; 493 out->stream.common.set_sample_rate = out_set_sample_rate; 494 out->stream.common.get_buffer_size = out_get_buffer_size; 495 out->stream.common.get_channels = out_get_channels; 496 out->stream.common.get_format = out_get_format; 497 out->stream.common.set_format = out_set_format; 498 out->stream.common.standby = out_standby; 499 out->stream.common.dump = out_dump; 500 out->stream.common.set_parameters = out_set_parameters; 501 out->stream.common.get_parameters = out_get_parameters; 502 out->stream.common.add_audio_effect = out_add_audio_effect; 503 out->stream.common.remove_audio_effect = out_remove_audio_effect; 504 out->stream.get_latency = out_get_latency; 505 out->stream.set_volume = out_set_volume; 506 out->stream.write = out_write; 507 out->stream.get_render_position = out_get_render_position; 508 out->stream.get_presentation_position = out_get_presentation_position; 509 out->stream.get_next_write_timestamp = out_get_next_write_timestamp; 510 511 pthread_mutex_init(&out->lock, (const pthread_mutexattr_t *) NULL); 512 pthread_mutex_init(&out->pre_lock, (const pthread_mutexattr_t *) NULL); 513 514 out->dev = adev; 515 pthread_mutex_lock(&adev->lock); 516 out->profile = &adev->out_profile; 517 518 // build this to hand to the alsa_device_proxy 519 struct pcm_config proxy_config; 520 memset(&proxy_config, 0, sizeof(proxy_config)); 521 522 /* Pull out the card/device pair */ 523 parse_card_device_params(address, &(out->profile->card), &(out->profile->device));... 526 527 profile_read_device_info(out->profile); 528 529 pthread_mutex_unlock(&adev->lock); 530 531 int ret = 0; 532 533 /* Rate */ 534 if (config->sample_rate == 0) { 535 proxy_config.rate = config->sample_rate = profile_get_default_sample_rate(out->profile); 536 } else if (profile_is_sample_rate_valid(out->profile, config->sample_rate)) { 537 proxy_config.rate = config->sample_rate; 538 } else {539 proxy_config.rate = config->sample_rate = profile_get_default_sample_rate(out->profile); 540 ret = -EINVAL; 541 } 542 543 /* Format */ 544 if (config->format == AUDIO_FORMAT_DEFAULT) { 545 proxy_config.format = profile_get_default_format(out->profile); 546 config->format = audio_format_from_pcm_format(proxy_config.format); 547 } else { 548 enum pcm_format fmt = pcm_format_from_audio_format(config->format); 549 if (profile_is_format_valid(out->profile, fmt)) { 550 proxy_config.format = fmt; 551 } else { 552 proxy_config.format = profile_get_default_format(out->profile); 553 config->format = audio_format_from_pcm_format(proxy_config.format); 554 ret = -EINVAL; 555 } 556 } 557 558 /* Channels */ 559 unsigned proposed_channel_count = 0; 560 if (k_force_channels) { 561 proposed_channel_count = k_force_channels; 562 } else if (config->channel_mask == AUDIO_CHANNEL_NONE) { 563 proposed_channel_count = profile_get_default_channel_count(out->profile); 564 } 565 if (proposed_channel_count != 0) { 566 if (proposed_channel_count <= FCC_2) { 567 // use channel position mask for mono and stereo 568 config->channel_mask = audio_channel_out_mask_from_count(proposed_channel_count); 569 } else { 570 // use channel index mask for multichannel 571 config->channel_mask = 572 audio_channel_mask_for_index_assignment_from_count(proposed_channel_count); 573 } 574 out->hal_channel_count = proposed_channel_count; 575 } else { 576 out->hal_channel_count = audio_channel_count_from_out_mask(config->channel_mask); 577 } 578 /* we can expose any channel mask, and emulate internally based on channel count. */ 579 out->hal_channel_mask = config->channel_mask; 580 581 /* no validity checks are needed as proxy_prepare() forces channel_count to be valid. 582 * and we emulate any channel count discrepancies in out_write(). */ 583 proxy_config.channels = proposed_channel_count; 584 585 proxy_prepare(&out->proxy, out->profile, &proxy_config); 586 587 /* TODO The retry mechanism isn't implemented in AudioPolicyManager/AudioFlinger. */ 588 ret = 0; 589 590 out->conversion_buffer = NULL; 591 out->conversion_buffer_size = 0; 592 593 out->standby = true; 594 595 *stream_out = &out->stream; 596 597 return ret;... 603 } 这个函数的整体流程还是比较好理解的，首先为创建的output stream关联一些函数操作集合，操作集包括了采样率/通道数/声音格式等这些信息。并且out_write会调用ALSA接口pcm_write写pcm数据。pcm_config<external/tinyalsa/include/asoundlib.h> 88 /* Configuration for a stream */ 89 struct pcm_config { 90 unsigned int channels; 91 unsigned int rate; 92 unsigned int period_size; 93 unsigned int period_count; 94 enum pcm_format format; 95 96 /* Values to use for the ALSA start, stop and silence thresholds, and 97 * silence size. Setting any one of these values to 0 will cause the 98 * default tinyalsa values to be used instead. 99 * Tinyalsa defaults are as follows.100 *101 * start_threshold : period_count * period_size102 * stop_threshold : period_count * period_size103 * silence_threshold : 0104 * silence_size : 0105 */106 unsigned int start_threshold;107 unsigned int stop_threshold;108 unsigned int silence_threshold;109 unsigned int silence_size;110 111 /* Minimum number of frames available before pcm_mmap_write() will actually112 * write into the kernel buffer. Only used if the stream is opened in mmap mode113 * (pcm_open() called with PCM_MMAP flag set). Use 0 for default.114 */115 int avail_min;116 };如果在初始化出问题，这个函数是需要跟踪。
ndroid 的USB支持已经由谷歌支持的很好了，基本上只需要开启内核的usb，如下图所示：
其所在的路径如下：
make ARCH=arm64 menuconfigDevice Drivers---> [*] Sound card support---> [*] Advanced Linux Sound Architecture ----> [*] USB sound devices-------------> [*] USB Audio/MIDI driver配置上述的选项后，则在/dev/snd目录会有声卡信息，并且使用tinyplay能够播放wav类型的音乐。接下来就是安卓层的设置了。
如果该系统有外接codec，则对于安卓6.0上层只需要开启USB host即可，但是如果只有usb这么一个声卡，则有些麻烦，因为audio policy会涉及到选择output stream的问题，output stream是有audio_policy.conf文件来指定的，主要来说就是配置文件中的primary和usb这两个声卡的信息填写方法。
usb host的使能方式是：
"device.mk" 587 lines --66%-- 391 PRODUCT_COPY_FILES += \392 frameworks/native/data/etc/android.hardware.usb.host.xml:system/etc/permissions/android.hardware.usb.host.xml \393 frameworks/native/data/etc/android.hardware.camera.xml:system/etc/permissions/android.hardware.camera.xml \394 frameworks/native/data/etc/android.hardware.camera.front.xml:system/etc/permissions/android.hardware.camera.front.xml \395 frameworks/native/data/etc/android.hardware.camera.flash-autofocus.xml:system/etc/permissions/android.hardware.camera.flash-autofocus.xml \396 frameworks/native/data/etc/android.hardware.camera.autofocus.xml:system/etc/permissions/android.hardware.camera.autofocus.xml \392行添加usb host权限文件即可，该文件实际上只有一行。device.mk是对应android根目录的device下具体型号设备的device.mk文件。
接着将该文件push到系统中reboot即可生效：
adb push frameworks/native/data/etc/android.hardware.usb.host.xml /system/etc/permissions/
USB的audio设备有两种类型一种是usb device一种是usb accessory，这两种设备的区别在于7420侧的usb所扮演的角色不同。如果7420做host，则其要和一个能做slave的设备连接，则在conf文件中，这样的设备被称为usb device，反之被称为usb accessory。其源码中的定义和说明位置如下：
604 /* USB accessory mode: your Android device is a USB device and the dock is a USB host */ 605 AUDIO_DEVICE_OUT_USB_ACCESSORY = 0x2000, 606 /* USB host mode: your Android device is a USB host and the dock is a USB device */ 607 AUDIO_DEVICE_OUT_USB_DEVICE = 0x4000, 608 AUDIO_DEVICE_OUT_REMOTE_SUBMIX = 0x8000, 609 /* Telephony voice TX path */ 610 AUDIO_DEVICE_OUT_TELEPHONY_TX = 0x10000,"system/media/audio/include/system/audio.h" 1446 lines --38%--所以在audio_policy.conf文件根据需要配置usb声卡信息；
usb { outputs { #usb_accessory { # sampling_rates 48000 # channel_masks AUDIO_CHANNEL_OUT_STEREO # formats AUDIO_FORMAT_PCM_16_BIT # devices AUDIO_DEVICE_OUT_USB_ACCESSORY #} usb_device { sampling_rates 48000 channel_masks AUDIO_CHANNEL_OUT_STEREO formats AUDIO_FORMAT_PCM_16_BIT devices AUDIO_DEVICE_OUT_USB_DEVICE } } }在audio_policy.conf文件中还有global_configuration字段，该字段的可以按如下方式填写：global_configuration { #attached_output_devices AUDIO_DEVICE_OUT_USB_ACCESSORY #default_output_device AUDIO_DEVICE_OUT_USB_ACCESSORY attached_output_devices AUDIO_DEVICE_OUT_USB_DEVICE default_output_device AUDIO_DEVICE_OUT_USB_DEVICE #attached_input_devices AUDIO_DEVICE_IN_BUILTIN_MIC}在调试过程中发现了如下错误：
01-01 16:16:14.220 V/AudioPolicyService( 3954): inserting command: 3 at index 0, num commands 001-01 16:16:14.220 V/AudioPolicyService( 3954): AudioCommandThread() processing set parameters string card=0;connect=16384;device=0, io 001-01 16:16:14.220 V/AudioFlinger( 3954): setParameters(): io 0, keyvalue card=0;connect=16384;device=0, calling pid 395401-01 16:16:14.220 V/AudioPolicyService( 3954): AudioCommandThread() going to sleep01-01 16:16:14.220 V/APM::AudioPolicyManager( 3954): checkOutputForStrategy() strategy 1, moving from output 4 to output 601-01 16:16:14.220 V/AudioFlinger( 3954): invalidateStream() stream 001-01 16:16:14.220 V/AudioFlinger( 3954): invalidateStream() stream 601-01 16:16:14.220 F/APM::AudioPolicyManager( 3954): const TYPE& android::SortedVector<TYPE>::operator[](size_t) const [with TYPE = int; size_t = unsigned int]: index=0 out of range (0)01-01 16:16:14.220 F/libc ( 3954): Fatal signal 6 (SIGABRT), code -6 in tid 3954 (mediaserver)01-01 16:16:14.320 F/DEBUG ( 2287): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***01-01 16:16:14.330 W/NativeCrashListener( 2595): Couldn't find ProcessRecord for pid 395401-01 16:16:14.320 F/DEBUG ( 2287): Build fingerprint: 'Android/full_phoenix/phoenix:6.0.1/MMB29T/gsc06080916:eng/dev-keys'01-01 16:16:14.320 F/DEBUG ( 2287): Revision: '0'01-01 16:16:14.320 F/DEBUG ( 2287): ABI: 'arm'01-01 16:16:14.320 F/DEBUG ( 2287): pid: 3954, tid: 3954, name: mediaserver >>> /system/bin/mediaserver <<<01-01 16:16:14.320 F/DEBUG ( 2287): signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------01-01 16:16:14.330 F/DEBUG ( 2287): Abort message: 'const TYPE& android::SortedVector<TYPE>::operator[](size_t) const [with TYPE = int; size_t = unsigned int]: index=0 out of range (0)'01-01 16:16:14.340 E/DEBUG ( 2287): AM write failed: Broken pipe01-01 16:16:14.340 F/DEBUG ( 2287): r0 00000000 r1 00000f72 r2 00000006 r3 f72f6b9401-01 16:16:14.340 F/DEBUG ( 2287): r4 f72f6b9c r5 f72f6b4c r6 00000000 r7 0000010c01-01 16:16:14.340 F/DEBUG ( 2287): r8 00000000 r9 f63f8014 sl ffbfbea4 fp f63ce75001-01 16:16:14.350 F/DEBUG ( 2287): ip 00000006 sp ffbfb9f0 lr f6dc528d pc f6dc767c cpsr 400f001001-01 16:16:14.360 F/DEBUG ( 2287): 01-01 16:16:14.360 F/DEBUG ( 2287): backtrace:01-01 16:16:14.370 F/DEBUG ( 2287): #00 pc 0004267c /system/lib/libc.so (tgkill+12)01-01 16:16:14.370 F/DEBUG ( 2287): #01 pc 00040289 /system/lib/libc.so (pthread_kill+32)01-01 16:16:14.370 F/DEBUG ( 2287): #02 pc 0001c9d3 /system/lib/libc.so (raise+10)01-01 16:16:14.370 F/DEBUG ( 2287): #03 pc 00019c51 /system/lib/libc.so (__libc_android_abort+34)01-01 16:16:14.370 F/DEBUG ( 2287): #04 pc 000174ac /system/lib/libc.so (abort+4)01-01 16:16:14.380 F/DEBUG ( 2287): #05 pc 00008173 /system/lib/libcutils.so (__android_log_assert+86)01-01 16:16:14.380 F/DEBUG ( 2287): #06 pc 00014d75 /system/lib/libaudiopolicymanagerdefault.so01-01 16:16:14.380 F/DEBUG ( 2287): #07 pc 0001bb95 /system/lib/libaudiopolicymanagerdefault.so (android::AudioPolicyManager::checkOutputForStrategy(android::routing_strategy)+268)01-01 16:16:14.380 F/DEBUG ( 2287): #08 pc 0001bd81 /system/lib/libaudiopolicymanagerdefault.so (android::AudioPolicyManager::checkOutputForAllStrategies()+56)01-01 16:16:14.380 F/DEBUG ( 2287): #09 pc 0001c3c5 /system/lib/libaudiopolicymanagerdefault.so (android::AudioPolicyManager::setDeviceConnectionStateInt(unsigned int, audio_policy_dev_state_t, char const*, char const*)+1548)01-01 16:16:14.380 F/DEBUG ( 2287): #10 pc 000097df /system/lib/libaudiopolicyservice.so01-01 16:16:14.380 F/DEBUG ( 2287): #11 pc 0008a981 /system/lib/libmedia.so (android::BnAudioPolicyService::onTransact(unsigned int, android::Parcel const&, android::Parcel*, unsigned int)+1164)01-01 16:16:14.380 F/DEBUG ( 2287): #12 pc 00019999 /system/lib/libbinder.so (android::BBinder::transact(unsigned int, android::Parcel const&, android::Parcel*, unsigned int)+60)01-01 16:16:14.380 F/DEBUG ( 2287): #13 pc 0001ecf9 /system/lib/libbinder.so (android::IPCThreadState::executeCommand(int)+560)01-01 16:16:14.390 F/DEBUG ( 2287): #14 pc 0001ee51 /system/lib/libbinder.so (android::IPCThreadState::getAndExecuteCommand()+64)01-01 16:16:14.390 F/DEBUG ( 2287): #15 pc 0001eeb5 /system/lib/libbinder.so (android::IPCThreadState::joinThreadPool(bool)+48)01-01 16:16:14.390 F/DEBUG ( 2287): #16 pc 00001bbb /system/bin/mediaserver01-01 16:16:14.390 F/DEBUG ( 2287): #17 pc 00017359 /system/lib/libc.so (__libc_init+44)01-01 16:16:14.390 F/DEBUG ( 2287): #18 pc 00001e0c /system/bin/mediaserver01-01 16:16:14.520 E/SurfaceFlinger( 2146): ro.sf.lcd_density must be defined as a build property这时定位问题就变的比较重要了。
gsc@gsc-250:/media/gsc/31269c00-69bd-4eed-814e-bade5758e213/7420_ext$ prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9/bin/aarch64-linux-android-addr2line -f -e out/target/product/phoenix/symbols/system/lib/libaudiopolicymanagerdefault.so 0001bb95_ZN7android18AudioPolicyManager22checkOutputForStrategyENS_16routing_strategyE/media/gsc/31269c00-69bd-4eed-814e-bade5758e213/7420_ext/frameworks/av/services/audiopolicy/managerdefault/AudioPolicyManager.cpp:3835 (discriminator 1)
临时动态推库调试：
1906 . build/envsetup.sh 1907 lunch 1908 mmm frameworks/av/services/audiopolicy/ 1909 adb remount 1910 adb push out/target/product/phoenix/system/lib/libaudiopolicymanagerdefault.so /system/lib/ 1911 adb push out/target/product/phoenix/system/lib64/libaudiopolicymanagerdefault.so /system/lib64/ 1912 adb push out/target/product/phoenix/system/lib64/libaudiopolicyservice.so /system/lib64/ 1913 adb push out/target/product/phoenix/system/lib/libaudiopolicyservice.so /system/lib/ 1926 mmm frameworks/av/services/audiopolicy/ 1927 adb remount 1928 adb push out/target/product/phoenix/system/lib64/libaudiopolicyenginedefault.so /system/lib64/ 1929 adb push out/target/product/phoenix/system/lib/libaudiopolicyenginedefault.so /system/lib/ 1954 mmm frameworks/av/services/audiopolicy/enginedefault/ 1955 adb push audio_policy.conf /system/etc/ 1956 adb push out/target/product/phoenix/system/lib64/libaudiopolicyenginedefault.so /system/lib64/ 1957 adb push out/target/product/phoenix/system/lib/libaudiopolicyenginedefault.so /system/lib/ 1960 mmm hardware/libhardware/modules/usbaudio/ 1961 mmm frameworks/av/services/audiopolicy/ 1962 adb remount 1963 adb push out/target/product/phoenix/system/lib/hw/audio.usb.default.so /system/lib/ 1964 adb push out/target/product/phoenix/system/lib64/hw/audio.usb.default.so /system/lib64/hw/ 1965 adb push out/target/product/phoenix/system/lib/hw/audio.usb.default.so /system/lib/hw/ 1966 adb push out/target/product/phoenix/system/lib/libaudiopolicymanagerdefault.so /system/lib/ 1967 adb push out/target/product/phoenix/system/lib64/libaudiopolicymanagerdefault.so /system/lib64/ 1968 adb reboot 1969 mmm hardware/libhardware/modules/usbaudio/ 1970 adb remount 1971 adb push out/target/product/phoenix/system/lib/hw/audio.usb.default.so /system/lib/hw/ 1972 adb push out/target/product/phoenix/system/lib64/hw/audio.usb.default.so /system/lib64/hw/ 1973 adb reboot
一点有用的代码分析
class AudioPolicyManager：<frameworks/av/services/audiopolicy/manager/default/AudioPolicyManager.h>
class AudioPolicyInterface: <frameworks/av/services/audiopolicy/AudioPolicyInterface.h>
class AudioPolicyManagerObserver
AudioPolicyService创建：
<frameworks/av/services/audiopolicy/service/AudioPolicyService.cpp>
在所有实际的操作前其会调用void AudioPolicyService::onFirstRef()
该函数调用了hardware层一些函数，也引用了hardware层一些函数，其定义在如下的函数中。
./hardware/libhardware/include/hardware/hardware.h
84行，未定义USE_LEGACY_AUDIO_POLICY，执行else语句分支。
114行~115行：
mAudioPolicyClient = new AudioPolicyClient(this);mAudioPolicyManager = createAudioPolicyManager(mAudioPolicyClient);
<AudioPolicyService.h>
AudioPolicyInterface *mAudioPolicyManager;AudioPolicyClient *mAudioPolicyClient;
<frameworks/av/services/audiopolicy/AudioPolicyInterface.h>
336~337行如下代码：
extern "C" AudioPolicyInterface* createAudioPolicyManager(AudioPolicyClientInterface *clientInterface);extern "C" void destroyAudioPolicyManager(AudioPolicyInterface *interface);
上述函数的实现位置是
<./frameworks/av/services/audiopolicy/manager/AudioPolicyFactory.cpp>
21 extern "C" AudioPolicyInterface* createAudioPolicyManager( 22 AudioPolicyClientInterface *clientInterface) 23 { 24 return new AudioPolicyManager(clientInterface); 25 }AudioPolicyManager函数定义在<frameworks/av/services/audiopolicy/managerdefault/AudioPolicyManager.cpp>
2712 AudioPolicyManager::AudioPolicyManager(AudioPolicyClientInterface *clientInterface)2713 :2714 #ifdef AUDIO_POLICY_TEST2715 Thread(false),2716 #endif //AUDIO_POLICY_TEST2717 mLimitRingtoneVolume(false), mLastVoiceVolume(-1.0f),2718 mA2dpSuspended(false),2719 mSpeakerDrcEnabled(false),2720 mAudioPortGeneration(1),2721 mBeaconMuteRefCount(0),2722 mBeaconPlayingRefCount(0),2723 mBeaconMuted(false),2724 mTtsOutputAvailable(false)2725 {2726 audio_policy::EngineInstance *engineInstance = audio_policy::EngineInstance::getInstance();2727 if (!engineInstance) {2728 ALOGE("%s: Could not get an instance of policy engine", __FUNCTION__);2729 return;2730 }2731 // Retrieve the Policy Manager Interface2732 mEngine = engineInstance->queryInterface<AudioPolicyManagerInterface>();2733 if (mEngine == NULL) {2734 ALOGE("%s: Failed to get Policy Engine Interface", __FUNCTION__);2735 return;2736 }2737 mEngine->setObserver(this);2738 status_t status = mEngine->initCheck();2739 ALOG_ASSERT(status == NO_ERROR, "Policy engine not initialized(err=%d)", status);2740 2741 mUidCached = getuid();2742 mpClientInterface = clientInterface;2743 2744 mDefaultOutputDevice = new DeviceDescriptor(AUDIO_DEVICE_OUT_SPEAKER);2745 if (ConfigParsingUtils::loadAudioPolicyConfig(AUDIO_POLICY_VENDOR_CONFIG_FILE,2746 mHwModules, mAvailableInputDevices, mAvailableOutputDevices,2747 mDefaultOutputDevice, mSpeakerDrcEnabled) != NO_ERROR) {2748 if (ConfigParsingUtils::loadAudioPolicyConfig(AUDIO_POLICY_CONFIG_FILE,2749 mHwModules, mAvailableInputDevices, mAvailableOutputDevices,2750 mDefaultOutputDevice, mSpeakerDrcEnabled) != NO_ERROR) {2751 ALOGE("could not load audio policy configuration file, setting defaults");2752 defaultAudioPolicyConfig();2753 }2754 }2755 // mAvailableOutputDevices and mAvailableInputDevices now contain all attached devices2756 2757 // must be done after reading the policy (since conditionned by Speaker Drc Enabling)2758 mEngine->initializeVolumeCurves(mSpeakerDrcEnabled);2759 2760 // open all output streams needed to access attached devices2761 audio_devices_t outputDeviceTypes = mAvailableOutputDevices.types();2762 audio_devices_t inputDeviceTypes = mAvailableInputDevices.types() & ~AUDIO_DEVICE_BIT_IN;2763 for (size_t i = 0; i < mHwModules.size(); i++) {2764 mHwModules[i]->mHandle = mpClientInterface->loadHwModule(mHwModules[i]->mName);2765 if (mHwModules[i]->mHandle == 0) {2766 ALOGW("could not open HW module %s", mHwModules[i]->mName);2767 continue;2768 }2769 // open all output streams needed to access attached devices2770 // except for direct output streams that are only opened when they are actually2771 // required by an app.2772 // This also validates mAvailableOutputDevices list2773 for (size_t j = 0; j < mHwModules[i]->mOutputProfiles.size(); j++)2774 {2775 const sp<IOProfile> outProfile = mHwModules[i]->mOutputProfiles[j];。。。2813 status_t status = mpClientInterface->openOutput(outProfile->getModuleHandle(),2814 &output,2815 &config,2816 &outputDesc->mDevice,2817 String8(""),2818 &outputDesc->mLatency,2819 outputDesc->mFlags);2820 2821 if (status != NO_ERROR) {2822 ALOGW("Cannot open output stream for device %08x on hw module %s",2823 outputDesc->mDevice,2824 mHwModules[i]->mName);2825 } else {2826 outputDesc->mSamplingRate = config.sample_rate;2827 outputDesc->mChannelMask = config.channel_mask;2828 outputDesc->mFormat = config.format;2829 2830 for (size_t k = 0; k < outProfile->mSupportedDevices.size(); k++) {2831 audio_devices_t type = outProfile->mSupportedDevices[k]->type();2832 ssize_t index =2833 mAvailableOutputDevices.indexOf(outProfile->mSupportedDevices[k]);2834 // give a valid ID to an attached device once confirmed it is reachable2835 if (index >= 0 && !mAvailableOutputDevices[index]->isAttached()) {2836 mAvailableOutputDevices[index]->attach(mHwModules[i]);2837 }2838 }2839 if (mPrimaryOutput == 0 &&2840 outProfile->mFlags & AUDIO_OUTPUT_FLAG_PRIMARY) {2841 mPrimaryOutput = outputDesc;2842 }2843 addOutput(output, outputDesc);2844 setOutputDevice(outputDesc,2845 outputDesc->mDevice,2846 true);2847 }2848 }2849 // open input streams needed to access attached devices to validate2850 // mAvailableInputDevices list2851 for (size_t j = 0; j < mHwModules[i]->mInputProfiles.size(); j++)2852 {2853 const sp<IOProfile> inProfile = mHwModules[i]->mInputProfiles[j];2854 2855 if (inProfile->mSupportedDevices.isEmpty()) {2856 ALOGW("Input profile contains no device on module %s", mHwModules[i]->mName);2857 continue;2858 }2859 // chose first device present in mSupportedDevices also part of2860 // inputDeviceTypes2861 audio_devices_t profileType = AUDIO_DEVICE_NONE;2862 for (size_t k = 0; k < inProfile->mSupportedDevices.size(); k++) {2863 profileType = inProfile->mSupportedDevices[k]->type();2864 if (profileType & inputDeviceTypes) {2865 break;2866 }2867 }2868 if ((profileType & inputDeviceTypes) == 0) {2869 continue;2870 }2871 sp<AudioInputDescriptor> inputDesc = new AudioInputDescriptor(inProfile);2872 2873 inputDesc->mInputSource = AUDIO_SOURCE_MIC;2874 inputDesc->mDevice = profileType;2875 2876 // find the address2877 DeviceVector inputDevices = mAvailableInputDevices.getDevicesFromType(profileType);2878 // the inputs vector must be of size 1, but we don't want to crash here2879 String8 address = inputDevices.size() > 0 ? inputDevices.itemAt(0)->mAddress2880 : String8("");2881 ALOGV(" for input device 0x%x using address %s", profileType, address.string());2882 ALOGE_IF(inputDevices.size() == 0, "Input device list is empty!");2883 2884 audio_config_t config = AUDIO_CONFIG_INITIALIZER;2885 config.sample_rate = inputDesc->mSamplingRate;2886 config.channel_mask = inputDesc->mChannelMask;2887 config.format = inputDesc->mFormat;2888 audio_io_handle_t input = AUDIO_IO_HANDLE_NONE;2889 status_t status = mpClientInterface->openInput(inProfile->getModuleHandle(),2890 &input,2891 &config,2892 &inputDesc->mDevice,2893 address,2894 AUDIO_SOURCE_MIC,2895 AUDIO_INPUT_FLAG_NONE);2896 2897 if (status == NO_ERROR) {2898 for (size_t k = 0; k < inProfile->mSupportedDevices.size(); k++) {2899 audio_devices_t type = inProfile->mSupportedDevices[k]->type();2900 ssize_t index =2901 mAvailableInputDevices.indexOf(inProfile->mSupportedDevices[k]);2902 // give a valid ID to an attached device once confirmed it is reachable2903 if (index >= 0) {2904 sp<DeviceDescriptor> devDesc = mAvailableInputDevices[index];2905 if (!devDesc->isAttached()) {2906 devDesc->attach(mHwModules[i]);2907 devDesc->importAudioPort(inProfile);2908 }2909 }2910 }2911 mpClientInterface->closeInput(input);2912 } else {2913 ALOGW("Cannot open input stream for device %08x on hw module %s",2914 inputDesc->mDevice,2915 mHwModules[i]->mName);2916 }2917 }2918 }2919 // make sure all attached devices have been allocated a unique ID2920 for (size_t i = 0; i < mAvailableOutputDevices.size();) {2921 if (!mAvailableOutputDevices[i]->isAttached()) {2922 ALOGW("Input device %08x unreachable", mAvailableOutputDevices[i]->type());2923 mAvailableOutputDevices.remove(mAvailableOutputDevices[i]);2924 continue;2925 }2926 // The device is now validated and can be appended to the available devices of the engine2927 mEngine->setDeviceConnectionState(mAvailableOutputDevices[i],2928 AUDIO_POLICY_DEVICE_STATE_AVAILABLE);2929 i++;2930 }2931 for (size_t i = 0; i < mAvailableInputDevices.size();) {2932 if (!mAvailableInputDevices[i]->isAttached()) {2933 ALOGW("Input device %08x unreachable", mAvailableInputDevices[i]->type());2934 mAvailableInputDevices.remove(mAvailableInputDevices[i]);2935 continue;2936 }2937 // The device is now validated and can be appended to the available devices of the engine2938 mEngine->setDeviceConnectionState(mAvailableInputDevices[i],2939 AUDIO_POLICY_DEVICE_STATE_AVAILABLE);2940 i++;2941 }2942 // make sure default device is reachable2943 if (mAvailableOutputDevices.indexOf(mDefaultOutputDevice) < 0) {2944 ALOGE("Default device %08x is unreachable", mDefaultOutputDevice->type());2945 }2946 2947 ALOGE_IF((mPrimaryOutput == 0), "Failed to open primary output");2948 2949 updateDevicesAndOutputs();2950 2951 #ifdef AUDIO_POLICY_TEST2952 if (mPrimaryOutput != 0) {2953 AudioParameter outputCmd = AudioParameter();2954 outputCmd.addInt(String8("set_id"), 0);2955 mpClientInterface->setParameters(mPrimaryOutput->mIoHandle, outputCmd.toString());2956 2957 mTestDevice = AUDIO_DEVICE_OUT_SPEAKER;2958 mTestSamplingRate = 44100;2959 mTestFormat = AUDIO_FORMAT_PCM_16_BIT;2960 mTestChannels = AUDIO_CHANNEL_OUT_STEREO;2961 mTestLatencyMs = 0;2962 mCurOutput = 0;2963 mDirectOutput = false;2964 for (int i = 0; i < NUM_TEST_OUTPUTS; i++) {2965 mTestOutputs[i] = 0;2966 }2967 2968 const size_t SIZE = 256;2969 char buffer[SIZE];2970 snprintf(buffer, SIZE, "AudioPolicyManagerTest");2971 run(buffer, ANDROID_PRIORITY_AUDIO);2972 }2973 #endif //AUDIO_POLICY_TEST2974 }2748行会解析/system/etc/audio_policy.conf配置文件，这是在找不到vendor定义的配置文件后的执行动作。
经过这个解析后，mAvailableOutputDevices和mAvailableInputDevices包括了所有的输出和输入设备。
2763行针对每一个设备进行加载。
2764行加载Hwmodule。
<frameworks/av/services/audioplolicy/AudioPolicyInterface.h>
class AudioPolicyClientInterface {...// loads a HW module. virtual audio_module_handle_t loadHwModule(const char *name) = 0;...}<./frameworks/av/services/audioflinger/AudioFlinger.cpp>
1561 audio_module_handle_t AudioFlinger::loadHwModule(const char *name)1562 {1563 if (name == NULL) {1564 return 0;1565 }1566 if (!settingsAllowed()) {1567 return 0;1568 }1569 Mutex::Autolock _l(mLock);1570 return loadHwModule_l(name);1571 }1572 1573 // loadHwModule_l() must be called with AudioFlinger::mLock held1574 audio_module_handle_t AudioFlinger::loadHwModule_l(const char *name)1575 {...1583 audio_hw_device_t *dev;1584 1585 int rc = load_audio_interface(name, &dev);1643 audio_module_handle_t handle = nextUniqueId();1644 mAudioHwDevs.add(handle, new AudioHwDevice(handle, name, dev, flags));1649 return handle;}load_audio_interface也定义在AudioFlinger函数里的定义如下：
140 static int load_audio_interface(const char *if_name, audio_hw_device_t **dev) 141 { 142 const hw_module_t *mod; 143 int rc; 144 145 rc = hw_get_module_by_class(AUDIO_HARDWARE_MODULE_ID, if_name, &mod); 151 rc = audio_hw_device_open(mod, dev); 167 }145行查看这类型的hw module是否存在，如果存在则会调用151行的open函数打开设备。
<./hardware/libhardware/include/hardware/audio.h>
680 static inline int audio_hw_device_open(const struct hw_module_t* module,681 struct audio_hw_device** device)682 {683 return module->methods->open(module, AUDIO_HARDWARE_INTERFACE,684 (struct hw_device_t**)device);685 }实际上的open函数定义于具体声卡类型的文件中，针对与usb audio设备，其定义于
<hardware/libhardware/modules/usbaudio/audio_hal.c>
1076 static struct hw_module_methods_t hal_module_methods = {1077 .open = adev_open,1078 };1079 1080 struct audio_module HAL_MODULE_INFO_SYM = {1081 .common = {1082 .tag = HARDWARE_MODULE_TAG,1083 .module_api_version = AUDIO_MODULE_API_VERSION_0_1,1084 .hal_api_version = HARDWARE_HAL_API_VERSION,1085 .id = AUDIO_HARDWARE_MODULE_ID,1086 .name = "USB audio HW HAL",1087 .author = "The Android Open Source Project",1088 .methods = &hal_module_methods,1089 },1090 };不出意外，这个open应该是成功的。接着打开流程loadHwModule的1644行。创建了一个硬件设备。该类的构造函数如下：
AudioHwDevice(audio_module_handle_t handle, const char *moduleName, audio_hw_device_t *hwDevice, Flags flags) : mHandle(handle) , mModuleName(strdup(moduleName)) , mHwDevice(hwDevice) , mFlags(flags) { }设备打开和添加的操作是完成了，接下来是打开对应的stream。AudioPolicyManager的2773行。
<./frameworks/av/services/audioflinger/AudioFlinger.cpp>
1775 sp<AudioFlinger::PlaybackThread> AudioFlinger::openOutput_l(audio_module_handle_t module,1776 audio_io_handle_t *output,1777 audio_config_t *config,1778 audio_devices_t devices,1779 const String8& address,1780 audio_output_flags_t flags)1781 {1782 AudioHwDevice *outHwDev = findSuitableHwDev_l(module, devices);1787 audio_hw_device_t *hwDevHal = outHwDev->hwDevice();1816 status_t status = outHwDev->openOutputStream(1817 &outputStream,1818 *output,1819 devices,1820 flags,1821 config,1822 address.string());...}1848 status_t AudioFlinger::openOutput(audio_module_handle_t module,1849 audio_io_handle_t *output,1850 audio_config_t *config,1851 audio_devices_t *devices,1852 const String8& address,1853 uint32_t *latencyMs,1854 audio_output_flags_t flags)1855 {1870 sp<PlaybackThread> thread = openOutput_l(module, output, config, *devices, address, flags);关键函数是1816行，打开stream。
<./frameworks/av/services/audioflinger/AudioHwDevice.cpp>
34 status_t AudioHwDevice::openOutputStream(35 AudioStreamOut **ppStreamOut, 36 audio_io_handle_t handle, 37 audio_devices_t devices, 38 audio_output_flags_t flags, 39 struct audio_config *config, 40 const char *address) 41 { 44 AudioStreamOut *outputStream = new AudioStreamOut(this, flags);status_t status = outputStream->open(handle, devices, config, address);AudioStreamOut类的作用是管理对HAL层output Stream的操作。
<./frameworks/av/services/audioflinger/AudioStreamOut.cpp>
112 status_t AudioStreamOut::open(113 audio_io_handle_t handle,114 audio_devices_t devices,115 struct audio_config *config,116 const char *address)117 {118 audio_stream_out_t *outStream;119 int status = hwDev()->open_output_stream(120 hwDev(),121 handle,122 devices,123 flags,124 config,125 &outStream,126 address);127 ALOGV("AudioStreamOut::open(), HAL open_output_stream returned "128 " %p, sampleRate %d, Format %#x, "129 "channelMask %#x, status %d",130 outStream,131 config->sample_rate,132 config->format,133 config->channel_mask,134 status);135 136 if (status == NO_ERROR) {137 stream = outStream;138 mHalFormatIsLinearPcm = audio_is_linear_pcm(config->format);139 ALOGI("AudioStreamOut::open(), mHalFormatIsLinearPcm = %d", (int)mHalFormatIsLinearPcm);140 mHalFrameSize = audio_stream_out_frame_size(stream);141 }142 143 return status;144 }AudioStreamOut.cpp文件里的绝大多数函数是调用HAL层代码完成其工作的。
上面的函数119行调用hardware/libhardware/modules/usbaudio/audio_hal.c的adev_open_output_stream完成实际的打开动作。
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