DMADESC_LENGTH_SHIFT
#define DMADESC_LENGTH_MASK (0xfff << DMADESC_LENGTH_SHIFT)
len_stat = priv->rx_buf_size << DMADESC_LENGTH_SHIFT;
len = (len_stat & DMADESC_LENGTH_MASK) >> DMADESC_LENGTH_SHIFT;
len_stat = (skb->len << DMADESC_LENGTH_SHIFT) & DMADESC_LENGTH_MASK;
dmaflags |= n_bytes << DMADESC_LENGTH_SHIFT;
dmaflags |= (1 << DMADESC_LENGTH_SHIFT) |
DMADESC_LENGTH_SHIFT;