插入耳机，先按音量键，再预览铃声的时候正常；但先预览铃声再按音量键的时候，音量偏大。

请在frameworks\av\services\audiopolicy\AudioPolicyManager.cpp

的AudioPolicyManager::computeVolume()的"volume = computeCustomVolume(stream, index, device);"之前添加如下代码：

int curDevice = getNewOutputDevice(output,false);
if(stream == AUDIO_STREAM_RING && device == AUDIO_DEVICE_OUT_SPEAKER &&
(curDevice & AUDIO_DEVICE_OUT_SPEAKER) &&
((curDevice & AUDIO_DEVICE_OUT_WIRED_HEADPHONE) || (curDevice & AUDIO_DEVICE_OUT_WIRED_HEADSET)))
{
ALOGD("computeVolume() stream %d, device %04x, curDevice %04x", stream, device, curDevice);
device = curDevice;
}