mv643xx_eth: get rid of modulo operations

Get rid of the modulo operations that are currently used for
computing successive TX/RX descriptor ring indexes.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>

diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 8c812c3..2f6cec4 100644 (file)
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -497,8 +497,10 @@ static void rxq_refill(struct rx_queue *rxq)
                        skb_reserve(skb, dma_get_cache_alignment() - unaligned);
 
                rxq->rx_desc_count++;
-               rx = rxq->rx_used_desc;
-               rxq->rx_used_desc = (rx + 1) % rxq->rx_ring_size;
+
+               rx = rxq->rx_used_desc++;
+               if (rxq->rx_used_desc == rxq->rx_ring_size)
+                       rxq->rx_used_desc = 0;
 
                rxq->rx_desc_area[rx].buf_ptr = dma_map_single(NULL, skb->data,
                                                skb_size, DMA_FROM_DEVICE);
@@ -555,7 +557,9 @@ static int rxq_process(struct rx_queue *rxq, int budget)
                skb = rxq->rx_skb[rxq->rx_curr_desc];
                rxq->rx_skb[rxq->rx_curr_desc] = NULL;
 
-               rxq->rx_curr_desc = (rxq->rx_curr_desc + 1) % rxq->rx_ring_size;
+               rxq->rx_curr_desc++;
+               if (rxq->rx_curr_desc == rxq->rx_ring_size)
+                       rxq->rx_curr_desc = 0;
 
                spin_unlock_irqrestore(&mp->lock, flags);
 
@@ -684,8 +688,9 @@ static int txq_alloc_desc_index(struct tx_queue *txq)
 
        BUG_ON(txq->tx_desc_count >= txq->tx_ring_size);
 
-       tx_desc_curr = txq->tx_curr_desc;
-       txq->tx_curr_desc = (tx_desc_curr + 1) % txq->tx_ring_size;
+       tx_desc_curr = txq->tx_curr_desc++;
+       if (txq->tx_curr_desc == txq->tx_ring_size)
+               txq->tx_curr_desc = 0;
 
        BUG_ON(txq->tx_curr_desc == txq->tx_used_desc);
 
@@ -1515,7 +1520,12 @@ static int rxq_init(struct mv643xx_eth_private *mp, int index)
 
        rx_desc = (struct rx_desc *)rxq->rx_desc_area;
        for (i = 0; i < rxq->rx_ring_size; i++) {
-               int nexti = (i + 1) % rxq->rx_ring_size;
+               int nexti;
+
+               nexti = i + 1;
+               if (nexti == rxq->rx_ring_size)
+                       nexti = 0;
+
                rx_desc[i].next_desc_ptr = rxq->rx_desc_dma +
                                        nexti * sizeof(struct rx_desc);
        }
@@ -1617,7 +1627,11 @@ static int txq_init(struct mv643xx_eth_private *mp, int index)
        tx_desc = (struct tx_desc *)txq->tx_desc_area;
        for (i = 0; i < txq->tx_ring_size; i++) {
                struct tx_desc *txd = tx_desc + i;
-               int nexti = (i + 1) % txq->tx_ring_size;
+               int nexti;
+
+               nexti = i + 1;
+               if (nexti == txq->tx_ring_size)
+                       nexti = 0;
 
                txd->cmd_sts = 0;
                txd->next_desc_ptr = txq->tx_desc_dma +
@@ -1663,7 +1677,9 @@ static void txq_reclaim(struct tx_queue *txq, int force)
                        desc->cmd_sts = cmd_sts & ~BUFFER_OWNED_BY_DMA;
                }
 
-               txq->tx_used_desc = (tx_index + 1) % txq->tx_ring_size;
+               txq->tx_used_desc = tx_index + 1;
+               if (txq->tx_used_desc == txq->tx_ring_size)
+                       txq->tx_used_desc = 0;
                txq->tx_desc_count--;
 
                addr = desc->buf_ptr;