dpaa_eth: cleanup skb_to_contig_fd()

Remove cast, align variable name, simplify DMA map size computation.
Signed-off-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/dpaa/dpaa_eth.c

@@ -1369,7 +1369,7 @@ static void count_ern(struct dpaa_percpu_priv *percpu_priv,
 static int dpaa_enable_tx_csum(struct dpaa_priv *priv,
 			       struct sk_buff *skb,
 			       struct qm_fd *fd,
-			       char *parse_results)
+			       void *parse_results)
 {
 	struct fman_prs_result *parse_result;
 	u16 ethertype = ntohs(skb->protocol);
@@ -1831,7 +1831,7 @@ static int skb_to_contig_fd(struct dpaa_priv *priv,
 {
 	struct net_device *net_dev = priv->net_dev;
 	enum dma_data_direction dma_dir;
-	unsigned char *buffer_start;
+	unsigned char *buff_start;
 	struct sk_buff **skbh;
 	dma_addr_t addr;
 	int err;
@@ -1840,10 +1840,10 @@ static int skb_to_contig_fd(struct dpaa_priv *priv,
 	 * available, so just use that for offset.
 	 */
 	fd->bpid = FSL_DPAA_BPID_INV;
-	buffer_start = skb->data - priv->tx_headroom;
+	buff_start = skb->data - priv->tx_headroom;
 	dma_dir = DMA_TO_DEVICE;
 
-	skbh = (struct sk_buff **)buffer_start;
+	skbh = (struct sk_buff **)buff_start;
 	*skbh = skb;
 
 	/* Enable L3/L4 hardware checksum computation.
@@ -1852,7 +1852,7 @@ static int skb_to_contig_fd(struct dpaa_priv *priv,
 	 * need to write into the skb.
 	 */
 	err = dpaa_enable_tx_csum(priv, skb, fd,
-				  ((char *)skbh) + DPAA_TX_PRIV_DATA_SIZE);
+				  buff_start + DPAA_TX_PRIV_DATA_SIZE);
 	if (unlikely(err < 0)) {
 		if (net_ratelimit())
 			netif_err(priv, tx_err, net_dev, "HW csum error: %d\n",
@@ -1865,8 +1865,8 @@ static int skb_to_contig_fd(struct dpaa_priv *priv,
 	fd->cmd |= cpu_to_be32(FM_FD_CMD_FCO);
 
 	/* Map the entire buffer size that may be seen by FMan, but no more */
-	addr = dma_map_single(priv->tx_dma_dev, skbh,
-			      skb_tail_pointer(skb) - buffer_start, dma_dir);
+	addr = dma_map_single(priv->tx_dma_dev, buff_start,
+			      priv->tx_headroom + skb->len, dma_dir);
 	if (unlikely(dma_mapping_error(priv->tx_dma_dev, addr))) {
 		if (net_ratelimit())
 			netif_err(priv, tx_err, net_dev, "dma_map_single() failed\n");