WATERMARK_MAX_RATIO
((hw_blocksize * (WATERMARK_MAX_RATIO + WATERMARK_RATIO_OUT))
+ (NEC86_BUFFSIZE * WATERMARK_MAX_RATIO - 1))
/ (NEC86_BUFFSIZE * WATERMARK_MAX_RATIO);
/ (sc->pdma_nchunk * WATERMARK_MAX_RATIO);
(NEC86_BUFFSIZE * WATERMARK_RATIO_IN) / WATERMARK_MAX_RATIO;