From patchwork Tue Oct 30 10:18:01 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Ferre X-Patchwork-Id: 195391 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id E9EF62C00B0 for ; Tue, 30 Oct 2012 21:19:58 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758725Ab2J3KTD (ORCPT ); Tue, 30 Oct 2012 06:19:03 -0400 Received: from eusmtp01.atmel.com ([212.144.249.242]:37187 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759278Ab2J3KS7 (ORCPT ); Tue, 30 Oct 2012 06:18:59 -0400 Received: from tenerife.corp.atmel.com (10.161.101.13) by eusmtp01.atmel.com (10.161.101.30) with Microsoft SMTP Server id 14.2.318.1; Tue, 30 Oct 2012 11:18:43 +0100 From: Nicolas Ferre To: , , CC: , , , , , , Nicolas Ferre Subject: [PATCH v3 09/10] net/macb: Offset first RX buffer by two bytes Date: Tue, 30 Oct 2012 11:18:01 +0100 Message-ID: X-Mailer: git-send-email 1.8.0 In-Reply-To: References: MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Havard Skinnemoen Make the ethernet frame payload word-aligned, possibly making the memcpy into the skb a bit faster. This will be even more important after we eliminate the copy altogether. Also eliminate the redundant RX_OFFSET constant -- it has the same definition and purpose as NET_IP_ALIGN. Signed-off-by: Havard Skinnemoen [nicolas.ferre@atmel.com: adapt to newer kernel] Signed-off-by: Nicolas Ferre --- drivers/net/ethernet/cadence/macb.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c index 83aa834..4d51877 100644 --- a/drivers/net/ethernet/cadence/macb.c +++ b/drivers/net/ethernet/cadence/macb.c @@ -33,9 +33,6 @@ #define RX_RING_SIZE 512 #define RX_RING_BYTES (sizeof(struct macb_dma_desc) * RX_RING_SIZE) -/* Make the IP header word-aligned (the ethernet header is 14 bytes) */ -#define RX_OFFSET 2 - #define TX_RING_SIZE 128 #define TX_RING_BYTES (sizeof(struct macb_dma_desc) * TX_RING_SIZE) @@ -498,7 +495,7 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag, { unsigned int len; unsigned int frag; - unsigned int offset = 0; + unsigned int offset; struct sk_buff *skb; struct macb_dma_desc *desc; @@ -509,7 +506,16 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag, macb_rx_ring_wrap(first_frag), macb_rx_ring_wrap(last_frag), len); - skb = netdev_alloc_skb(bp->dev, len + RX_OFFSET); + /* + * The ethernet header starts NET_IP_ALIGN bytes into the + * first buffer. Since the header is 14 bytes, this makes the + * payload word-aligned. + * + * Instead of calling skb_reserve(NET_IP_ALIGN), we just copy + * the two padding bytes into the skb so that we avoid hitting + * the slowpath in memcpy(), and pull them off afterwards. + */ + skb = netdev_alloc_skb(bp->dev, len + NET_IP_ALIGN); if (!skb) { bp->stats.rx_dropped++; for (frag = first_frag; ; frag++) { @@ -525,7 +531,8 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag, return 1; } - skb_reserve(skb, RX_OFFSET); + offset = 0; + len += NET_IP_ALIGN; skb_checksum_none_assert(skb); skb_put(skb, len); @@ -549,10 +556,11 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag, /* Make descriptor updates visible to hardware */ wmb(); + __skb_pull(skb, NET_IP_ALIGN); skb->protocol = eth_type_trans(skb, bp->dev); bp->stats.rx_packets++; - bp->stats.rx_bytes += len; + bp->stats.rx_bytes += skb->len; netdev_vdbg(bp->dev, "received skb of length %u, csum: %08x\n", skb->len, skb->csum); netif_receive_skb(skb); @@ -1012,6 +1020,7 @@ static void macb_init_hw(struct macb *bp) __macb_set_hwaddr(bp); config = macb_mdc_clk_div(bp); + config |= MACB_BF(RBOF, NET_IP_ALIGN); /* Make eth data aligned */ config |= MACB_BIT(PAE); /* PAuse Enable */ config |= MACB_BIT(DRFCS); /* Discard Rx FCS */ config |= MACB_BIT(BIG); /* Receive oversized frames */