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