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From: Felix Fietkau <nbd@openwrt.org>
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Date: Sun, 12 Apr 2015 10:13:28 +0200
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Subject: [PATCH] bgmac: set received skb headroom to NET_SKB_PAD
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A packet buffer offset of 30 bytes is inefficient, because the first 2
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bytes end up in a different cacheline.
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Signed-off-by: Felix Fietkau <nbd@openwrt.org>
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---
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--- a/drivers/net/ethernet/broadcom/bgmac.c
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+++ b/drivers/net/ethernet/broadcom/bgmac.c
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@@ -346,13 +346,13 @@ static int bgmac_dma_rx_skb_for_slot(str
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return -ENOMEM;
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/* Poison - if everything goes fine, hardware will overwrite it */
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- rx = buf;
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+ rx = buf + BGMAC_RX_BUF_OFFSET;
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rx->len = cpu_to_le16(0xdead);
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rx->flags = cpu_to_le16(0xbeef);
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/* Map skb for the DMA */
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- dma_addr = dma_map_single(dma_dev, buf, BGMAC_RX_BUF_SIZE,
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- DMA_FROM_DEVICE);
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+ dma_addr = dma_map_single(dma_dev, buf + BGMAC_RX_BUF_OFFSET,
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+ BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
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if (dma_mapping_error(dma_dev, dma_addr)) {
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bgmac_err(bgmac, "DMA mapping error\n");
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put_page(virt_to_head_page(buf));
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@@ -403,7 +403,7 @@ static int bgmac_dma_rx_read(struct bgma
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while (ring->start != ring->end) {
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struct device *dma_dev = bgmac->core->dma_dev;
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struct bgmac_slot_info *slot = &ring->slots[ring->start];
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- struct bgmac_rx_header *rx = slot->buf;
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+ struct bgmac_rx_header *rx = slot->buf + BGMAC_RX_BUF_OFFSET;
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struct sk_buff *skb;
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void *buf = slot->buf;
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u16 len, flags;
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@@ -454,8 +454,10 @@ static int bgmac_dma_rx_read(struct bgma
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BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
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skb = build_skb(buf, BGMAC_RX_ALLOC_SIZE);
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- skb_put(skb, BGMAC_RX_FRAME_OFFSET + len);
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- skb_pull(skb, BGMAC_RX_FRAME_OFFSET);
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+ skb_put(skb, BGMAC_RX_FRAME_OFFSET +
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+ BGMAC_RX_BUF_OFFSET + len);
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+ skb_pull(skb, BGMAC_RX_FRAME_OFFSET +
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+ BGMAC_RX_BUF_OFFSET);
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skb_checksum_none_assert(skb);
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skb->protocol = eth_type_trans(skb, bgmac->net_dev);
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--- a/drivers/net/ethernet/broadcom/bgmac.h
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+++ b/drivers/net/ethernet/broadcom/bgmac.h
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@@ -360,9 +360,11 @@
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#define BGMAC_RX_HEADER_LEN 28 /* Last 24 bytes are unused. Well... */
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#define BGMAC_RX_FRAME_OFFSET 30 /* There are 2 unused bytes between header and real data */
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+#define BGMAC_RX_BUF_OFFSET (NET_SKB_PAD + NET_IP_ALIGN - \
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+ BGMAC_RX_FRAME_OFFSET)
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#define BGMAC_RX_MAX_FRAME_SIZE 1536 /* Copied from b44/tg3 */
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#define BGMAC_RX_BUF_SIZE (BGMAC_RX_FRAME_OFFSET + BGMAC_RX_MAX_FRAME_SIZE)
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-#define BGMAC_RX_ALLOC_SIZE (SKB_DATA_ALIGN(BGMAC_RX_BUF_SIZE) + \
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+#define BGMAC_RX_ALLOC_SIZE (SKB_DATA_ALIGN(BGMAC_RX_BUF_SIZE + BGMAC_RX_BUF_OFFSET) + \
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SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
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#define BGMAC_BFL_ENETROBO 0x0010 /* has ephy roboswitch spi */
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