CS_RING_SIZE
csdma = csring->chan.ring_dma + (fill & (CS_RING_SIZE-1)) * 8 + 2;
csring->next_to_fill = fill & (CS_RING_SIZE-1);
ring->size = CS_RING_SIZE;
if (pasemi_dma_alloc_ring(&ring->chan, CS_RING_SIZE))
val |= PAS_DMA_TXCHAN_BASEU_SIZ(CS_RING_SIZE >> 3);
#define CS_DESC(cs, num) ((cs)->chan.ring_virt[(num) & (CS_RING_SIZE-1)])