BWI_TXSTATS_NDESC
dma_size = roundup(desc_sz * BWI_TXSTATS_NDESC, BWI_RING_ALIGN);
dma_size = roundup(sizeof(struct bwi_txstats) * BWI_TXSTATS_NDESC,
bzero(st->stats, BWI_TXSTATS_NDESC * sizeof(struct bwi_txstats));
for (i = 0; i < BWI_TXSTATS_NDESC; ++i) {
bwi_setup_desc32(sc, st->stats_ring, BWI_TXSTATS_NDESC, i,
st->stats_ring_paddr, 0, BWI_TXSTATS_NDESC);
idx = (idx + 1) % BWI_TXSTATS_NDESC;