ocelot_fdma_idx_dma
dcb->llp = ocelot_fdma_idx_dma(rx_ring->dcbs_dma, idx);
new_llp = ocelot_fdma_idx_dma(dma_base, idx);
dma = ocelot_fdma_idx_dma(tx_ring->dcbs_dma, tx_ring->next_to_clean);
dma = ocelot_fdma_idx_dma(tx_ring->dcbs_dma,
dcb->llp = ocelot_fdma_idx_dma(tx_ring->dcbs_dma, next_idx);