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>

1 files changed, 24 insertions, 8 deletions

diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 8c812c3d1b7d..2f6cec4e8499 100644
--- 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;