HDA_DMA_ACCESS_LEN
assert(!(count % HDA_DMA_ACCESS_LEN));
buf += HDA_DMA_ACCESS_LEN;
st->bp += HDA_DMA_ACCESS_LEN;
lpib += HDA_DMA_ACCESS_LEN;
left -= HDA_DMA_ACCESS_LEN;
assert(!(bdle_sz % HDA_DMA_ACCESS_LEN));