记录一下高通音频配置文件mixer_paths.xml初始化过程。参考代码基于Android O。
hardware/qcom/audio/hal/audio_hw.c
struct audio_module HAL_MODULE_INFO_SYM = {
.common = {
.tag = HARDWARE_MODULE_TAG,
.module_api_version = AUDIO_MODULE_API_VERSION_0_1,
.hal_api_version = HARDWARE_HAL_API_VERSION,
.id = AUDIO_HARDWARE_MODULE_ID,
.name = "QCOM Audio HAL",
.author = "The Linux Foundation",
.methods = &hal_module_methods,
},
};
对应操作方法
static struct hw_module_methods_t hal_module_methods = {
.open = adev_open,
};
static int adev_open(const hw_module_t *module, const char *name,
hw_device_t **device)
{
......
adev->platform = platform_init(adev); // 平台初始化函数
if (!adev->platform) {
free(adev->snd_dev_ref_cnt);
free(adev);
ALOGE("%s: Failed to init platform data, aborting.", __func__);
*device = NULL;
pthread_mutex_unlock(&adev_init_lock);
pthread_mutex_destroy(&adev->lock);
return -EINVAL;
}
......
}
根据不同的芯片找到对应的文件
hardware/qcom/audio/hal/msm8916/platform.c
void *platform_init(struct audio_device *adev)
{
char value[PROPERTY_VALUE_MAX];
struct platform_data *my_data = NULL;
int snd_card_num = 0;
const char *snd_card_name;
char mixer_xml_path[MAX_MIXER_XML_PATH],ffspEnable[PROPERTY_VALUE_MAX];
const char *mixer_ctl_name = "Set HPX ActiveBe";
struct mixer_ctl *ctl = NULL;
int idx;
int wsaCount =0;
bool is_wsa_combo_supported = false;
snd_card_num = audio_extn_utils_get_snd_card_num(); //获取声卡的的编号
if(snd_card_num < 0) {
ALOGE("%s: Unable to find correct sound card", __func__);
return NULL;
}
adev->snd_card = snd_card_num;
ALOGD("%s: Opened sound card:%d", __func__, snd_card_num);
adev->mixer = mixer_open(snd_card_num);
if (!adev->mixer) {
ALOGE("%s: Unable to open the mixer card: %d", __func__,
snd_card_num);
return NULL;
}
snd_card_name = mixer_get_name(adev->mixer);
ALOGD("%s: snd_card_name: %s", __func__, snd_card_name);
my_data = calloc(1, sizeof(struct platform_data));
if (!my_data) {
ALOGE("failed to allocate platform data");
return NULL;
}
my_data->hw_info = hw_info_init(snd_card_name); //初始化hw_info结构体
if (!my_data->hw_info) {
ALOGE("%s: Failed to init hardware info", __func__);
free(my_data);
return NULL;
}
query_platform(snd_card_name, mixer_xml_path); //query_platform,根据设备名称找到xml文件的路径
ALOGD("%s: mixer path file is %s", __func__,
mixer_xml_path);
if (audio_extn_read_xml(adev, snd_card_num, mixer_xml_path,
MIXER_XML_PATH_AUXPCM) == -ENOSYS) {
adev->audio_route = audio_route_init(snd_card_num, // 解析xml文件
mixer_xml_path);
}
if (!adev->audio_route) {
ALOGE("%s: Failed to init audio route controls, aborting.",
__func__);
free(my_data);
mixer_close(adev->mixer);
return NULL;
}
update_codec_type(snd_card_name);
update_interface(snd_card_name);
......
}
query_platform定义如下
static void query_platform(const char *snd_card_name,
char *mixer_xml_path)
{
if (!strncmp(snd_card_name, "msm8x16-snd-card-mtp",
sizeof("msm8x16-snd-card-mtp"))) {
strlcpy(mixer_xml_path, MIXER_XML_PATH_MTP,
sizeof(MIXER_XML_PATH_MTP));
msm_device_to_be_id = msm_device_to_be_id_internal_codec;
msm_be_id_array_len =
sizeof(msm_device_to_be_id_internal_codec) / sizeof(msm_device_to_be_id_internal_codec[0]);
......
} else if (!strncmp(snd_card_name, "msm8953-snd-card-mtp", // 根据设备名称使用不同的xml文件
sizeof("msm8953-snd-card-mtp"))) {
strlcpy(mixer_xml_path, MIXER_XML_PATH_MTP,
sizeof(MIXER_XML_PATH_MTP));
msm_device_to_be_id = msm_device_to_be_id_internal_codec;
msm_be_id_array_len =
sizeof(msm_device_to_be_id_internal_codec) / sizeof(msm_device_to_be_id_internal_codec[0]);
......
}
设备名称通过可以在adb中查看cat /proc/asound/cards，如下：
Tony:/ # cat /proc/asound/cards
cat /proc/asound/cards
0 [msm8953sndcardm]: msm8953-snd-car - msm8953-snd-card-mtp
msm8953-snd-card-mtp
因此可以知道选取的文件
#define MIXER_XML_PATH_MTP "/etc/mixer_paths_mtp.xml"
xml文件解析函数位于system/media/audio_route/audio_route.c
struct audio_route *audio_route_init(unsigned int card, const char *xml_path)
{
struct config_parse_state state;
XML_Parser parser;
FILE *file;
int bytes_read;
void *buf;
struct audio_route *ar;
ar = calloc(1, sizeof(struct audio_route));
if (!ar)
goto err_calloc;
ar->mixer = mixer_open(card);
if (!ar->mixer) {
ALOGE("Unable to open the mixer, aborting.");
goto err_mixer_open;
}
ar->mixer_path = NULL;
ar->mixer_path_size = 0;
ar->num_mixer_paths = 0;
/* allocate space for and read current mixer settings */
if (alloc_mixer_state(ar) < 0)
goto err_mixer_state;
/* use the default XML path if none is provided */
if (xml_path == NULL)
xml_path = MIXER_XML_PATH;
file = fopen(xml_path, "r");
if (!file) {
ALOGE("Failed to open %s: %s", xml_path, strerror(errno));
parser = XML_ParserCreate(NULL);
if (!parser) {
ALOGE("Failed to create XML parser");
goto err_parser_create;
}
memset(&state, 0, sizeof(state));
state.ar = ar;
XML_SetUserData(parser, &state);
XML_SetElementHandler(parser, start_tag, end_tag);
for (;;) {
buf = XML_GetBuffer(parser, BUF_SIZE);
if (buf == NULL)
goto err_parse;
bytes_read = fread(buf, 1, BUF_SIZE, file);
if (bytes_read < 0)
goto err_parse;
if (XML_ParseBuffer(parser, bytes_read,
bytes_read == 0) == XML_STATUS_ERROR) {
ALOGE("Error in mixer xml (%s)", MIXER_XML_PATH);
goto err_parse;
}
if (bytes_read == 0)
break;
}
/* apply the initial mixer values, and save them so we can reset the
mixer to the original values */
audio_route_update_mixer(ar);
save_mixer_state(ar);
XML_ParserFree(parser);
fclose(file);
return ar;
......
}
xml位于源码位置hardware/qcom/audio/configs/msm8953/
xml文件存放的路径更改了,android O的路径位于/vendor/etc/下面，android N位于/system/etc/
mixer_paths_mtp.xml分析，可参考http://bbs.gfan.com/android-7626545-1-1.html
文件的开头会写一些默认的参数，也就是
然后不同的设备，也就是不同的
<?xml version="1.0" encoding="ISO-8859-1"?>
<mixer>
<!-- These are the initial mixer settings -->
<ctl name="Voice Rx Device Mute" id="0" value="0" />
<ctl name="Voice Rx Device Mute" id="1" value="-1" />
<ctl name="Voice Rx Device Mute" id="2" value="20" />
<ctl name="Voice Tx Mute" id="0" value="0" />
<ctl name="Voice Tx Mute" id="1" value="-1" />
<ctl name="Voice Tx Mute" id="2" value="500" />
<ctl name="Voice Rx Gain" id="0" value="0" />
<ctl name="Voice Rx Gain" id="1" value="-1" />
<ctl name="Voice Rx Gain" id="2" value="20" />
......
<path name="handset"> <!-- 电话听筒 -->
<ctl name="RX1 MIX1 INP1" value="RX1" />
<ctl name="RDAC2 MUX" value="RX1" />
<ctl name="RX1 Digital Volume" value="84" />
<ctl name="EAR PA Gain" value="POS_6_DB" />
<ctl name="EAR_S" value="Switch" />
</path>
<path name="handset-mic">
<path name="adc1" />
<ctl name="IIR1 INP1 MUX" value="DEC1" />
</path>
<path name="headphones"> <!-- 耳机 -->
<ctl name="MI2S_RX Channels" value="Two" />
<ctl name="RX1 MIX1 INP1" value="RX1" />
<ctl name="RX2 MIX1 INP1" value="RX2" />
<ctl name="RX HPH Mode" value="HD2" />
<ctl name="COMP0 RX1" value="1" />
<ctl name="COMP0 RX2" value="1" />
<ctl name="RDAC2 MUX" value="RX2" />
<ctl name="HPHL" value="Switch" />
<ctl name="HPHR" value="Switch" />
</path>
<path name="headset-mic">
<path name="adc2" />
<ctl name="ADC2 MUX" value="INP2" />
<ctl name="IIR1 INP1 MUX" value="DEC1" />
</path>
......
Tony Liu
2018-1-29