Hi Clemens,

Your answer is very useful to help me. Thank you very much.

case AUDIO_STREAM_CMDID_DATARXTXREQ:

      len1 = get_zsp_buf_avail(&prtd->zsp_buf);

      len2 = get_fw_avail(p_zsp_req, substream->stream);

      len3 = get_buf_avail(&prtd->zsp_buf, substream->stream);

      tsize = ((len1 < len2) ? len1 : len2);

      if ((tsize == len1) && (len1 == len3) && (tsize >= \

            2 * prtd->zsp_buf.zsp_period_bytes)) {

            tsize -= prtd->zsp_buf.zsp_period_bytes;

      }

This doesn't look as if tsize is always the same as the period size.

And what do the get_fw_avail and get_buf_avail functions do?

The ZSP have own buffer to save data, so get_fw_avail is acquired zsp buf avial.

And ZSP buffer must ensure the zsp_buf have sequenced, so do above process.

-- Best Regards, Zhen Fu