target/linux/generic/patches-3.18/077-07-bgmac-simplify-rx-DMA-error-handling.patch

   1 From: Felix Fietkau <nbd@openwrt.org>
   2 Date: Sun, 12 Apr 2015 22:23:07 +0200
   3 Subject: [PATCH] bgmac: simplify/optimize rx DMA error handling
   4
   5 Allocate a new buffer before processing the completed one. If allocation
   6 fails, reuse the old buffer.
   7
   8 Signed-off-by: Felix Fietkau <nbd@openwrt.org>
   9 ---
  10
  11 --- a/drivers/net/ethernet/broadcom/bgmac.c
  12 +++ b/drivers/net/ethernet/broadcom/bgmac.c
  13 @@ -386,6 +386,19 @@ static void bgmac_dma_rx_setup_desc(stru
  14         dma_desc->ctl1 = cpu_to_le32(ctl1);
  15  }
  16
  17 +static void bgmac_dma_rx_poison_buf(struct device *dma_dev,
  18 +                                   struct bgmac_slot_info *slot)
  19 +{
  20 +       struct bgmac_rx_header *rx = slot->buf + BGMAC_RX_BUF_OFFSET;
  21 +
  22 +       dma_sync_single_for_cpu(dma_dev, slot->dma_addr, BGMAC_RX_BUF_SIZE,
  23 +                               DMA_FROM_DEVICE);
  24 +       rx->len = cpu_to_le16(0xdead);
  25 +       rx->flags = cpu_to_le16(0xbeef);
  26 +       dma_sync_single_for_device(dma_dev, slot->dma_addr, BGMAC_RX_BUF_SIZE,
  27 +                                  DMA_FROM_DEVICE);
  28 +}
  29 +
  30  static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
  31                              int weight)
  32  {
  33 @@ -406,53 +419,35 @@ static int bgmac_dma_rx_read(struct bgma
  34                 struct bgmac_rx_header *rx = slot->buf + BGMAC_RX_BUF_OFFSET;
  35                 struct sk_buff *skb;
  36                 void *buf = slot->buf;
  37 +               dma_addr_t dma_addr = slot->dma_addr;
  38                 u16 len, flags;
  39
  40 -               /* Unmap buffer to make it accessible to the CPU */
  41 -               dma_sync_single_for_cpu(dma_dev, slot->dma_addr,
  42 -                                       BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
  43 -
  44 -               /* Get info from the header */
  45 -               len = le16_to_cpu(rx->len);
  46 -               flags = le16_to_cpu(rx->flags);
  47 -
  48                 do {
  49 -                       dma_addr_t old_dma_addr = slot->dma_addr;
  50 -                       int err;
  51 +                       /* Prepare new skb as replacement */
  52 +                       if (bgmac_dma_rx_skb_for_slot(bgmac, slot)) {
  53 +                               bgmac_dma_rx_poison_buf(dma_dev, slot);
  54 +                               break;
  55 +                       }
  56 +
  57 +                       /* Unmap buffer to make it accessible to the CPU */
  58 +                       dma_unmap_single(dma_dev, dma_addr,
  59 +                                        BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
  60 +
  61 +                       /* Get info from the header */
  62 +                       len = le16_to_cpu(rx->len);
  63 +                       flags = le16_to_cpu(rx->flags);
  64
  65                         /* Check for poison and drop or pass the packet */
  66                         if (len == 0xdead && flags == 0xbeef) {
  67                                 bgmac_err(bgmac, "Found poisoned packet at slot %d, DMA issue!\n",
  68                                           ring->start);
  69 -                               dma_sync_single_for_device(dma_dev,
  70 -                                                          slot->dma_addr,
  71 -                                                          BGMAC_RX_BUF_SIZE,
  72 -                                                          DMA_FROM_DEVICE);
  73 +                               put_page(virt_to_head_page(buf));
  74                                 break;
  75                         }
  76
  77                         /* Omit CRC. */
  78                         len -= ETH_FCS_LEN;
  79
  80 -                       /* Prepare new skb as replacement */
  81 -                       err = bgmac_dma_rx_skb_for_slot(bgmac, slot);
  82 -                       if (err) {
  83 -                               /* Poison the old skb */
  84 -                               rx->len = cpu_to_le16(0xdead);
  85 -                               rx->flags = cpu_to_le16(0xbeef);
  86 -
  87 -                               dma_sync_single_for_device(dma_dev,
  88 -                                                          slot->dma_addr,
  89 -                                                          BGMAC_RX_BUF_SIZE,
  90 -                                                          DMA_FROM_DEVICE);
  91 -                               break;
  92 -                       }
  93 -                       bgmac_dma_rx_setup_desc(bgmac, ring, ring->start);
  94 -
  95 -                       /* Unmap old skb, we'll pass it to the netfif */
  96 -                       dma_unmap_single(dma_dev, old_dma_addr,
  97 -                                        BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
  98 -
  99                         skb = build_skb(buf, BGMAC_RX_ALLOC_SIZE);
 100                         skb_put(skb, BGMAC_RX_FRAME_OFFSET +
 101                                 BGMAC_RX_BUF_OFFSET + len);
 102 @@ -465,6 +460,8 @@ static int bgmac_dma_rx_read(struct bgma
 103                         handled++;
 104                 } while (0);
 105
 106 +               bgmac_dma_rx_setup_desc(bgmac, ring, ring->start);
 107 +
 108                 if (++ring->start >= BGMAC_RX_RING_SLOTS)
 109                         ring->start = 0;
 110
 111 @@ -532,14 +529,14 @@ static void bgmac_dma_rx_ring_free(struc
 112
 113         for (i = 0; i < ring->num_slots; i++) {
 114                 slot = &ring->slots[i];
 115 -               if (!slot->buf)
 116 +               if (!slot->dma_addr)
 117                         continue;
 118
 119 -               if (slot->dma_addr)
 120 -                       dma_unmap_single(dma_dev, slot->dma_addr,
 121 -                                        BGMAC_RX_BUF_SIZE,
 122 -                                        DMA_FROM_DEVICE);
 123 +               dma_unmap_single(dma_dev, slot->dma_addr,
 124 +                                BGMAC_RX_BUF_SIZE,
 125 +                                DMA_FROM_DEVICE);
 126                 put_page(virt_to_head_page(slot->buf));
 127 +               slot->dma_addr = 0;
 128         }
 129  }
 130