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Commit b17d1559 authored by Jisheng Zhang's avatar Jisheng Zhang Committed by David S. Miller
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net: pxa168_eth: Use dma_wmb/rmb where appropriate 



Update the pxa168_eth driver to use the dma_rmb/wmb calls instead of the
full barriers in order to improve performance: reduced 97ns/39ns on
average in tx/rx path on Marvell BG4CT platform.

Signed-off-by: default avatarJisheng Zhang <jszhang@marvell.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3ed68782

drivers/net/ethernet/marvell/pxa168_eth.c

+4 −4
Original line number Diff line number Diff line
@@ -342,9 +342,9 @@ static void rxq_refill(struct net_device *dev) 
		pep->rx_skb[used_rx_desc] = skb;



		/* Return the descriptor to DMA ownership */

		wmb();

		dma_wmb();

		p_used_rx_desc->cmd_sts = BUF_OWNED_BY_DMA | RX_EN_INT;

		wmb();

		dma_wmb();



		/* Move the used descriptor pointer to the next descriptor */

		pep->rx_used_desc_q = (used_rx_desc + 1) % pep->rx_ring_size;
@@ -794,7 +794,7 @@ static int rxq_process(struct net_device *dev, int budget) 
		rx_used_desc = pep->rx_used_desc_q;

		rx_desc = &pep->p_rx_desc_area[rx_curr_desc];

		cmd_sts = rx_desc->cmd_sts;

		rmb();

		dma_rmb();

		if (cmd_sts & (BUF_OWNED_BY_DMA))

			break;

		skb = pep->rx_skb[rx_curr_desc];
@@ -1287,7 +1287,7 @@ static int pxa168_eth_start_xmit(struct sk_buff *skb, struct net_device *dev) 


	skb_tx_timestamp(skb);



	wmb();

	dma_wmb();

	desc->cmd_sts = BUF_OWNED_BY_DMA | TX_GEN_CRC | TX_FIRST_DESC |

			TX_ZERO_PADDING | TX_LAST_DESC | TX_EN_INT;

	wmb();