OpenWrt – Rev 4

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From: Felix Fietkau <nbd@nbd.name>
Date: Mon, 23 Mar 2015 02:41:25 +0100
Subject: [PATCH] bgmac: implement GRO and use build_skb

This improves performance for routing and local rx

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
@@ -276,31 +276,31 @@ static int bgmac_dma_rx_skb_for_slot(str
                                     struct bgmac_slot_info *slot)
 {
        struct device *dma_dev = bgmac->core->dma_dev;
-       struct sk_buff *skb;
        dma_addr_t dma_addr;
        struct bgmac_rx_header *rx;
+       void *buf;
 
        /* Alloc skb */
-       skb = netdev_alloc_skb(bgmac->net_dev, BGMAC_RX_BUF_SIZE);
-       if (!skb)
+       buf = netdev_alloc_frag(BGMAC_RX_ALLOC_SIZE);
+       if (!buf)
                return -ENOMEM;
 
        /* Poison - if everything goes fine, hardware will overwrite it */
-       rx = (struct bgmac_rx_header *)skb->data;
+       rx = buf;
        rx->len = cpu_to_le16(0xdead);
        rx->flags = cpu_to_le16(0xbeef);
 
        /* Map skb for the DMA */
-       dma_addr = dma_map_single(dma_dev, skb->data,
-                                 BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
+       dma_addr = dma_map_single(dma_dev, buf, BGMAC_RX_BUF_SIZE,
+                                 DMA_FROM_DEVICE);
        if (dma_mapping_error(dma_dev, dma_addr)) {
                bgmac_err(bgmac, "DMA mapping error\n");
-               dev_kfree_skb(skb);
+               put_page(virt_to_head_page(buf));
                return -ENOMEM;
        }
 
        /* Update the slot */
-       slot->skb = skb;
+       slot->buf = buf;
        slot->dma_addr = dma_addr;
 
        return 0;
@@ -343,8 +343,9 @@ 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 sk_buff *skb = slot->skb;
-               struct bgmac_rx_header *rx;
+               struct bgmac_rx_header *rx = slot->buf;
+               struct sk_buff *skb;
+               void *buf = slot->buf;
                u16 len, flags;
 
                /* Unmap buffer to make it accessible to the CPU */
@@ -352,7 +353,6 @@ static int bgmac_dma_rx_read(struct bgma
                                        BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
 
                /* Get info from the header */
-               rx = (struct bgmac_rx_header *)skb->data;
                len = le16_to_cpu(rx->len);
                flags = le16_to_cpu(rx->flags);
 
@@ -393,12 +393,13 @@ static int bgmac_dma_rx_read(struct bgma
                        dma_unmap_single(dma_dev, old_dma_addr,
                                         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_checksum_none_assert(skb);
                        skb->protocol = eth_type_trans(skb, bgmac->net_dev);
-                       netif_receive_skb(skb);
+                       napi_gro_receive(&bgmac->napi, skb);
                        handled++;
                } while (0);
 
@@ -434,12 +435,11 @@ static bool bgmac_dma_unaligned(struct b
        return false;
 }
 
-static void bgmac_dma_ring_free(struct bgmac *bgmac,
-                               struct bgmac_dma_ring *ring)
+static void bgmac_dma_tx_ring_free(struct bgmac *bgmac,
+                                  struct bgmac_dma_ring *ring)
 {
        struct device *dma_dev = bgmac->core->dma_dev;
        struct bgmac_slot_info *slot;
-       int size;
        int i;
 
        for (i = 0; i < ring->num_slots; i++) {
@@ -451,23 +451,55 @@ static void bgmac_dma_ring_free(struct b
                        dev_kfree_skb(slot->skb);
                }
        }
+}
+
+static void bgmac_dma_rx_ring_free(struct bgmac *bgmac,
+                                  struct bgmac_dma_ring *ring)
+{
+       struct device *dma_dev = bgmac->core->dma_dev;
+       struct bgmac_slot_info *slot;
+       int i;
+
+       for (i = 0; i < ring->num_slots; i++) {
+               slot = &ring->slots[i];
+               if (!slot->buf)
+                       continue;
 
-       if (ring->cpu_base) {
-               /* Free ring of descriptors */
-               size = ring->num_slots * sizeof(struct bgmac_dma_desc);
-               dma_free_coherent(dma_dev, size, ring->cpu_base,
-                                 ring->dma_base);
+               if (slot->dma_addr)
+                       dma_unmap_single(dma_dev, slot->dma_addr,
+                                        BGMAC_RX_BUF_SIZE,
+                                        DMA_FROM_DEVICE);
+               put_page(virt_to_head_page(slot->buf));
        }
 }
 
+static void bgmac_dma_ring_desc_free(struct bgmac *bgmac,
+                                    struct bgmac_dma_ring *ring)
+{
+       struct device *dma_dev = bgmac->core->dma_dev;
+       int size;
+
+       if (!ring->cpu_base)
+           return;
+
+       /* Free ring of descriptors */
+       size = ring->num_slots * sizeof(struct bgmac_dma_desc);
+       dma_free_coherent(dma_dev, size, ring->cpu_base,
+                         ring->dma_base);
+}
+
 static void bgmac_dma_free(struct bgmac *bgmac)
 {
        int i;
 
-       for (i = 0; i < BGMAC_MAX_TX_RINGS; i++)
-               bgmac_dma_ring_free(bgmac, &bgmac->tx_ring[i]);
-       for (i = 0; i < BGMAC_MAX_RX_RINGS; i++)
-               bgmac_dma_ring_free(bgmac, &bgmac->rx_ring[i]);
+       for (i = 0; i < BGMAC_MAX_TX_RINGS; i++) {
+               bgmac_dma_tx_ring_free(bgmac, &bgmac->tx_ring[i]);
+               bgmac_dma_ring_desc_free(bgmac, &bgmac->tx_ring[i]);
+       }
+       for (i = 0; i < BGMAC_MAX_RX_RINGS; i++) {
+               bgmac_dma_rx_ring_free(bgmac, &bgmac->rx_ring[i]);
+               bgmac_dma_ring_desc_free(bgmac, &bgmac->rx_ring[i]);
+       }
 }
 
 static int bgmac_dma_alloc(struct bgmac *bgmac)
--- a/drivers/net/ethernet/broadcom/bgmac.h
+++ b/drivers/net/ethernet/broadcom/bgmac.h
@@ -362,6 +362,8 @@
 #define BGMAC_RX_FRAME_OFFSET                  30              /* There are 2 unused bytes between header and real data */
 #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) + \
+                                                SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
 
 #define BGMAC_BFL_ENETROBO                     0x0010          /* has ephy roboswitch spi */
 #define BGMAC_BFL_ENETADM                      0x0080          /* has ADMtek switch */
@@ -383,7 +385,10 @@
 #define ETHER_MAX_LEN   1518
 
 struct bgmac_slot_info {
-       struct sk_buff *skb;
+       union {
+               struct sk_buff *skb;
+               void *buf;
+       };
        dma_addr_t dma_addr;
 };