ARM: DaVinci: EMAC: remove "extra" bytes provision in rx buffer

The provision for extra bytes in each rx buffer was meant for allocators
who cannot guarantee cacheline aligned buffer allocation.

cacheline aligned allocation is guaranteed by alloc_skb so this provision is
not required.

This should save 32*128 = 4k of space.

Tested on DM6446 EVM using NFS root, iperf (TCP) and tftp of a gigabyte of data.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

drivers/net/davinci_emac.c

@@ -125,10 +125,8 @@ static const char emac_version_string[] = "TI DaVinci EMAC Linux v6.0";
 #define EMAC_DEF_TXPACING_EN		(0) /* TX pacing NOT supported*/
 
 #define EMAC_DEF_BUFFER_OFFSET		(0) /* Buffer offset to DMA (future) */
-#define EMAC_DEF_EXTRA_RXBUF_SIZE	(32)/* Extra bytes in each RX packet */
 #define EMAC_DEF_MIN_ETHPKTSIZE		(60) /* Minimum ethernet pkt size */
-#define EMAC_DEF_MAX_FRAME_SIZE		(1500 + 14 + 4 + 4 + \
-					 (EMAC_DEF_EXTRA_RXBUF_SIZE))
+#define EMAC_DEF_MAX_FRAME_SIZE		(1500 + 14 + 4 + 4)
 #define EMAC_DEF_TX_CH			(0) /* Default 0th channel */
 #define EMAC_DEF_RX_CH			(0) /* Default 0th channel */
 #define EMAC_DEF_MDIO_TICK_MS		(10) /* typically 1 tick=1 ms) */
@@ -1560,7 +1558,6 @@ static void *emac_net_alloc_rx_buf(struct emac_priv *priv, int buf_size,
 
 	/* set device pointer in skb and reserve space for extra bytes */
 	p_skb->dev = ndev;
-	skb_reserve(p_skb, EMAC_DEF_EXTRA_RXBUF_SIZE);
 	*data_token = (void *) p_skb;
 	EMAC_CACHE_WRITEBACK_INVALIDATE((unsigned long)p_skb->data, buf_size);
 	return p_skb->data;
@@ -2411,7 +2408,7 @@ static int emac_dev_open(struct net_device *ndev)
 		ndev->dev_addr[cnt] = priv->mac_addr[cnt];
 
 	/* Configuration items */
-	priv->rx_buf_size = EMAC_DEF_MAX_FRAME_SIZE + EMAC_DEF_EXTRA_RXBUF_SIZE;
+	priv->rx_buf_size = EMAC_DEF_MAX_FRAME_SIZE;
 
 	/* Clear basic hardware */
 	for (ch = 0; ch < EMAC_MAX_TXRX_CHANNELS; ch++) {