audio driver

List,

I am not sure if it is a right place to ask audio interface question . 

I create a HDMI interface for TI davinic SoC. But capture file, my.wav, size is only 44 bytes after "arecord my.wav".

1. "arecord -l" display interface as:

root@c6a816x-evm:~# arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: hdmi [TI81XX hdmi], device 0: HDMI McASP Receive hdmi_sii9135-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

2. root@c6a816x-evm:/dev/snd# ls
controlC0  pcmC0D0c   timer

I check sound/soc/davinci and see snd_pcm_lib_ioctl() is useless.

Could anyone please give me hint where to start debug?

Thanks.

---henry