Android6.0----关于USB麦克风框架

最近遇到一个问题：插入带麦克风的USB摄像头，摄像头可以正常输出图像但是没有声音，跟踪了一下整个框架记录一下

先从kernel入手：

kernel/sound/usb/card.c

当插入USB麦克风，USB Core会通过注册的usb_audio_ids 匹配到usb_audio_probe()函数

static struct usb_device_id usb_audio_ids [] = {

#include "quirks-table.h"

{ .match_flags = (USB_DEVICE_ID_MATCH_INT_CLASS | USB_DEVICE_ID_MATCH_INT_SUBCLASS),

.bInterfaceClass = USB_CLASS_AUDIO,

.bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL },

{ } /* Terminating entry */

};

MODULE_DEVICE_TABLE(usb, usb_audio_ids);

/*

* entry point for linux usb interface

*/

static struct usb_driver usb_audio_driver = {

.name = "snd-usb-audio",

.probe = usb_audio_probe,

.disconnect = usb_audio_disconnect,

.suspend = usb_audio_suspend,

.resume = usb_audio_resume,

.id_table = usb_audio_ids,

.supports_autosuspend = 1,

};

static int usb_audio_probe(struct usb_interface *intf,

const struct usb_device_id *id)

{

struct snd_usb_audio *chip;

chip = snd_usb_audio_probe(interface_to_usbdev(intf), intf, id);

if (chip) {

usb_set_intfdata(intf, chip);

return 0;

} else

return -EIO;

}

snd_usb_audio_probe()函数会调用snd_usb_create_quirk（）

static struct snd_usb_audio * snd_usb_audio_probe(struct usb_device *dev,struct usb_interface *intf,const struct usb_device_id *usb_id)

{

。。。。。。。。。。。。。。。。。。。

if (!chip->ctrl_intf)

chip->ctrl_intf = alts;

chip->txfr_quirk = 0;

err = 1; /* continue */

if (quirk && quirk->ifnum != QUIRK_NO_INTERFACE) {

/* need some special handlings */

if ((err = snd_usb_create_quirk(chip, intf, &usb_audio_driver, quirk)) < 0)

goto __error;

}

if (err > 0) {

/* create normal USB audio interfaces */

if (snd_usb_create_streams(chip, ifnum) < 0 ||

snd_usb_create_mixer(chip, ifnum, ignore_ctl_error) < 0) {

goto __error;

}

/* we are allowed to call snd_card_register() many times */

if (snd_card_register(chip->card) < 0) {

goto __error;

}

。。。。。。。。。。。。。。。。。。。。。。。。。。

}

int snd_usb_create_quirk(struct snd_usb_audio *chip,struct usb_interface *iface,struct usb_driver *driver,const struct snd_usb_audio_quirk *quirk)

{

typedef int (*quirk_func_t)(struct snd_usb_audio *,

struct usb_interface *,

struct usb_driver *,

const struct snd_usb_audio_quirk *);

static const quirk_func_t quirk_funcs[] = {

[QUIRK_IGNORE_INTERFACE] = ignore_interface_quirk,

[QUIRK_COMPOSITE] = create_composite_quirk,

[QUIRK_MIDI_STANDARD_INTERFACE] = create_any_midi_quirk,

[QUIRK_MIDI_FIXED_ENDPOINT] = create_any_midi_quirk,

[QUIRK_MIDI_YAMAHA] = create_any_midi_quirk,

[QUIRK_MIDI_MIDIMAN] = create_any_midi_quirk,

[QUIRK_MIDI_NOVATION] = create_any_midi_quirk,

[QUIRK_MIDI_RAW_BYTES] = create_any_midi_quirk,

[QUIRK_MIDI_EMAGIC] = create_any_midi_quirk,

[QUIRK_MIDI_CME] = create_any_midi_quirk,

[QUIRK_MIDI_AKAI] = create_any_midi_quirk,

[QUIRK_MIDI_FTDI] = create_any_midi_quirk,

[QUIRK_AUDIO_STANDARD_INTERFACE] = create_standard_audio_quirk,

[QUIRK_AUDIO_FIXED_ENDPOINT] = create_fixed_stream_quirk,

[QUIRK_AUDIO_EDIROL_UAXX] = create_uaxx_quirk,

[QUIRK_AUDIO_ALIGN_TRANSFER] = create_align_transfer_quirk,

[QUIRK_AUDIO_STANDARD_MIXER] = create_standard_mixer_quirk,

};

if (quirk->type < QUIRK_TYPE_COUNT) {

return quirk_funcs[quirk->type](chip, iface, driver, quirk);

} else {

snd_printd(KERN_ERR "invalid quirk type %d\n", quirk->type);

return -ENXIO;

}

static int create_uaxx_quirk(struct snd_usb_audio *chip,

struct usb_interface *iface,

struct usb_driver *driver,

const struct snd_usb_audio_quirk *quirk)

{

。。。。。。

err = snd_usb_add_audio_stream(chip, stream, fp);

。。。。。。

}

int snd_usb_add_audio_stream(struct snd_usb_audio *chip,

int stream,

struct audioformat *fp)

{

err = snd_pcm_new(chip->card, "USB Audio", chip->pcm_devs,

stream == SNDRV_PCM_STREAM_PLAYBACK ? 1 : 0,

stream == SNDRV_PCM_STREAM_PLAYBACK ? 0 : 1,

&pcm);

}

static int _snd_pcm_new(struct snd_card *card, const char *id, int device,

int playback_count, int capture_count, bool internal,

struct snd_pcm **rpcm)

{

struct snd_pcm *pcm;

int err;

static struct snd_device_ops ops = {

.dev_free = snd_pcm_dev_free,

.dev_register = snd_pcm_dev_register,

.dev_disconnect = snd_pcm_dev_disconnect,

};

if (snd_BUG_ON(!card))

return -ENXIO;

if (rpcm)

*rpcm = NULL;

pcm = kzalloc(sizeof(*pcm), GFP_KERNEL);

if (pcm == NULL) {

snd_printk(KERN_ERR "Cannot allocate PCM\n");

return -ENOMEM;

}

pcm->card = card;

pcm->device = device;

pcm->internal = internal;

}

static int snd_pcm_dev_register(struct snd_device *device)

{

int cidx, err;

struct snd_pcm_substream *substream;

struct snd_pcm_notify *notify;

char str[16];

struct snd_pcm *pcm;

struct device *dev;

if (snd_BUG_ON(!device || !device->device_data))

return -ENXIO;

pcm = device->device_data;

mutex_lock(®ister_mutex);

err = snd_pcm_add(pcm);

if (err) {

mutex_unlock(®ister_mutex);

return err;

}

for (cidx = 0; cidx < 2; cidx++) {

int devtype = -1;

if (pcm->streams[cidx].substream == NULL || pcm->internal)

continue;

switch (cidx) {

case SNDRV_PCM_STREAM_PLAYBACK:

sprintf(str, "pcmC%iD%ip", pcm->card->number, pcm->device);

devtype = SNDRV_DEVICE_TYPE_PCM_PLAYBACK;

break;

case SNDRV_PCM_STREAM_CAPTURE:

sprintf(str, "pcmC%iD%ic", pcm->card->number, pcm->device);

devtype = SNDRV_DEVICE_TYPE_PCM_CAPTURE;

break;

}

/* device pointer to use, pcm->dev takes precedence if

* it is assigned, otherwise fall back to card's device

* if possible */

dev = pcm->dev;

if (!dev)

dev = snd_card_get_device_link(pcm->card);

/* register pcm */

err = snd_register_device_for_dev(devtype, pcm->card,

pcm->device,

&snd_pcm_f_ops[cidx],

pcm, str, dev);

if (err < 0) {

list_del(&pcm->list);

mutex_unlock(®ister_mutex);

return err;

}

snd_add_device_sysfs_file(devtype, pcm->card, pcm->device,

&pcm_attrs);

for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)

snd_pcm_timer_init(substream);

}

list_for_each_entry(notify, &snd_pcm_notify_list, list)

notify->n_register(pcm);

mutex_unlock(®ister_mutex);

return 0;

}

最终会在: /dev/snd/pcm* 创建出节点。

进入framework/base/services/usb/java/com/android/server/usb/UsbAlsaManager.java

private static final String ALSA_DIRECTORY = "/dev/snd/";

private final FileObserver mAlsaObserver = new FileObserver(ALSA_DIRECTORY,

FileObserver.CREATE | FileObserver.DELETE) {

public void onEvent(int event, String path) {

switch (event) {

case FileObserver.CREATE:

alsaFileAdded(path);

break;

case FileObserver.DELETE:

alsaFileRemoved(path);

break;

}

};

当/dev/snd/目录下有新的设备节点创建时调用：alsaFileAdded()

private void alsaFileAdded(String name) {

int type = AlsaDevice.TYPE_UNKNOWN;

int card = -1, device = -1;

if (name.startsWith("pcmC")) {

if (name.endsWith("p")) {

type = AlsaDevice.TYPE_PLAYBACK;

} else if (name.endsWith("c")) {

type = AlsaDevice.TYPE_CAPTURE;

}

} else if (name.startsWith("midiC")) {

type = AlsaDevice.TYPE_MIDI;

}

if (type != AlsaDevice.TYPE_UNKNOWN) {

try {

int c_index = name.indexOf('C');

int d_index = name.indexOf('D');

int end = name.length();

if (type == AlsaDevice.TYPE_PLAYBACK || type == AlsaDevice.TYPE_CAPTURE) {

// skip trailing 'p' or 'c'

end--;

}

card = Integer.parseInt(name.substring(c_index + 1, d_index));

device = Integer.parseInt(name.substring(d_index + 1, end));

} catch (Exception e) {

Slog.e(TAG, "Could not parse ALSA file name " + name, e);

return;

}

synchronized(mAlsaDevices) {

if (mAlsaDevices.get(name) == null) {

AlsaDevice alsaDevice = new AlsaDevice(type, card, device);

Slog.d(TAG, "Adding ALSA device " + alsaDevice);

mAlsaDevices.put(name, alsaDevice);

mAlsaDevices.notifyAll();

}

最后会调到：usbDeviceAdded()

void usbDeviceAdded(UsbDevice usbDevice) {

...................................

ArrayList prevScanRecs = mCardsParser.getScanRecords();

mCardsParser.scan();

mCardsParser.scan()的时候会读取声卡生成记录系统有多少逻辑设备的文件：/proc/asound/cards

cat /proc/asound/cards 信息如下：

0 [msm8939sndcards]: msm8939-snd-car - msm8939-snd-card-skuk

msm8939-snd-card-skuk

1 [C170 ]: USB-Audio - Webcam C170

Webcam C170 at usb-msm_hsusb_host-1.4.1, high speed

public void scan() {

if (DEBUG) { Slog.i(TAG, "AlsaCardsParser.scan()"); } mCardRecords = new ArrayList();

File cardsFile = new File(kCardsFilePath); //kCardsFilePath=/proc/asound/cards

try {

FileReader reader = new FileReader(cardsFile);

BufferedReader bufferedReader = new BufferedReader(reader);

String line = "";

while ((line = bufferedReader.readLine()) != null) {

AlsaCardRecord cardRecord = new AlsaCardRecord();

cardRecord.parse(line, 0);

line = bufferedReader.readLine();

if (line == null) {

break;

}

cardRecord.parse(line, 1);

mCardRecords.add(cardRecord);

}

reader.close();

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

..................................

if (mCardsParser.isCardUsb(addedCard)) {

UsbAudioDevice audioDevice = selectAudioCard(addedCard);

if (audioDevice != null) {

mAudioDevices.put(usbDevice, audioDevice);

}

..................................

}

UsbAudioDevice selectAudioCard(int card) {

..................................

notifyDeviceState(audioDevice, true);

...................................

}

private void notifyDeviceState(UsbAudioDevice audioDevice, boolean enabled) {

...........................

// Capture Device

if (audioDevice.mHasCapture) {

int device = (audioDevice == mAccessoryAudioDevice ?

AudioSystem.DEVICE_IN_USB_ACCESSORY :

AudioSystem.DEVICE_IN_USB_DEVICE);

mAudioService.setWiredDeviceConnectionState(

device, state, address, audioDevice.mDeviceName, TAG);

}

...........................

}

frameworks/base/services/core/java/com/android/server/audio/AudioService.java

public void setWiredDeviceConnectionState(int type, int state, String address, String name,

String caller) {

synchronized (mConnectedDevices) {

int delay = checkSendBecomingNoisyIntent(type, state);

queueMsgUnderWakeLock(mAudioHandler,

MSG_SET_WIRED_DEVICE_CONNECTION_STATE,

new WiredDeviceConnectionState(type, state, address, name, caller),

delay);

}

public void handleMessage(Message msg) {

..............................

case MSG_SET_WIRED_DEVICE_CONNECTION_STATE:

{ WiredDeviceConnectionState connectState =

(WiredDeviceConnectionState)msg.obj;

onSetWiredDeviceConnectionState(connectState.mType, connectState.mState,

connectState.mAddress, connectState.mName, connectState.mCaller);

mAudioEventWakeLock.release();

}

break;

..............................

}

private void onSetWiredDeviceConnectionState(int device, int state, String address,

String deviceName, String caller) {

.............................................................

boolean isUsb = ((device & ~AudioSystem.DEVICE_OUT_ALL_USB) == 0) ||

(((device & AudioSystem.DEVICE_BIT_IN) != 0) &&

((device & ~AudioSystem.DEVICE_IN_ALL_USB) == 0));

if (!handleDeviceConnection(state == 1, device, address, deviceName)) {

// change of connection state failed, bailout

return;

}

............................................................

}

private boolean handleDeviceConnection(boolean connect, int device, String address,

String deviceName) {

........................................

if (connect && !isConnected) {//第一次连接走这里

final int res = AudioSystem.setDeviceConnectionState(device,

AudioSystem.DEVICE_STATE_AVAILABLE, address, deviceName);

if (res != AudioSystem.AUDIO_STATUS_OK) {

Slog.e(TAG, "not connecting device 0x" + Integer.toHexString(device) +

" due to command error " + res );

return false;

}

mConnectedDevices.put(deviceKey, new DeviceListSpec(device, deviceName, address));

return true;

} else if (!connect && isConnected) {//断开走这里

AudioSystem.setDeviceConnectionState(device,

AudioSystem.DEVICE_STATE_UNAVAILABLE, address, deviceName);

// always remove even if disconnection failed

mConnectedDevices.remove(deviceKey);

return true;

}

..........................................

}

frameworks/base/media/java/android/media/AudioSystem.java

public static native int setDeviceConnectionState(int device, int state,

String device_address, String device_name);

通过JNI调到：frameworks/base/core/jni/android_media_AudioSystem.cpp

static jintandroid_media_AudioSystem_setDeviceConnectionState(JNIEnv *env, jobject thiz, jint device, jint state, jstring device_address, jstring device_name){ const char *c_address = env->GetStringUTFChars(device_address, NULL); const char *c_name = env->GetStringUTFChars(device_name, NULL); int status = check_AudioSystem_Command(AudioSystem::setDeviceConnectionState(static_cast(device), static_cast(state),

c_address, c_name));

env->ReleaseStringUTFChars(device_address, c_address);

env->ReleaseStringUTFChars(device_name, c_name);

return (jint) status;

}

frameworks/av/media/libmedia/AudioSystem.cpp

status_t AudioSystem::setDeviceConnectionState(audio_devices_t device, audio_policy_dev_state_t state, const char *device_address, const char *device_name){ const sp& aps = AudioSystem::get_audio_policy_service();

const char *address = "";

const char *name = "";

if (aps == 0) return PERMISSION_DENIED;

if (device_address != NULL) {

address = device_address;

}

if (device_name != NULL) {

name = device_name;

}

return aps->setDeviceConnectionState(device, state, address, name);

}

最终调到：

hardware\qcom\audio\policy_hal\AudioPolicyManager.cpp

status_t AudioPolicyManagerCustom::setDeviceConnectionStateInt(audio_devices_t device,

audio_policy_dev_state_t state,

const char *device_address,

const char *device_name)

{

..........................................................

// handle input devices if (audio_is_input_device(device)) { SortedVectorinputs; ssize_t index = mAvailableInputDevices.indexOf(devDesc); switch (state) { // handle input device connection case AUDIO_POLICY_DEVICE_STATE_AVAILABLE: { if (index >= 0) { ALOGW("setDeviceConnectionState() device already connected: %d", device); return INVALID_OPERATION; } sp module = mHwModules.getModuleForDevice(device);

if (module == NULL) {

ALOGW("setDeviceConnectionState(): could not find HW module for device %08x",

device);

return INVALID_OPERATION;

}

if (checkInputsForDevice(devDesc, state, inputs, devDesc->mAddress) != NO_ERROR) {

return INVALID_OPERATION;

}

index = mAvailableInputDevices.add(devDesc);//添加到可用输入设备列表中待选

if (index >= 0) {

mAvailableInputDevices[index]->attach(module);

} else {

return NO_MEMORY;

}

// Set connect to HALs

AudioParameter param = AudioParameter(devDesc->mAddress);

param.addInt(String8(AUDIO_PARAMETER_DEVICE_CONNECT), device);

mpClientInterface->setParameters(AUDIO_IO_HANDLE_NONE, param.toString());

// Propagate device availability to Engine

mEngine->setDeviceConnectionState(devDesc, state);

} break;

..........................................................

}

没有插入USB麦克风是输入设备列表LOG如下：

APM::Devices: Device id:5 type:0x80000004:Built-In Mic, addr: