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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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