mtk6572 用内部功放，怎么把音频声音调节大些

status_t AudioMachineDevice::SetAmpGain(AudioAnalogType::VOLUME_TYPE volume_Type, int volume)
{
    // this will base on hw spec, use 15dB for
    uint32 index =  13;
    // condition for gainb not mute
    if(volume > 11){
        volume = 11;
    }
    //const int HWgain[] =  {-60,0,4,5,6,7,8,9,10,11,12,13,14,15,16,17};
    index -= volume;
    if (index < 1) {
        index= 1; // min to 0dB
    }
    ALOGD("jianghuiyan SetAmpGain volume_Type = %d volume = %d,index=%d",volume_Type,volume,index);
    index = 15; //SPK 17dB jianghuiyan 20130528
    if(volume_Type == AudioAnalogType::VOLUME_SPKL ||volume_Type == AudioAnalogType::VOLUME_SPKR)
    {
        mAudioAnalogReg->SetAnalogReg(SPK_CON9,index<<8,0x00000f00);
    }
    return NO_ERROR;
}