target/linux/mediatek/patches-4.4/0090-net-next-mediatek-fix-off-by-one-in-the-TX-ring-allo.patch

   1 From 94425de9ede5ef0eafbfced65140c30e7c0b6c0d Mon Sep 17 00:00:00 2001
   2 From: John Crispin <john@phrozen.org>
   3 Date: Tue, 3 May 2016 03:01:13 +0200
   4 Subject: [PATCH 090/102] net-next: mediatek: fix off by one in the TX ring
   5  allocation
   6
   7 The TX ring setup has an off by one error causing it to not utilise all
   8 descriptors. This has the side effect that we need to reset the next
   9 pointer at runtime to make it work. Fix the off by one and remove the
  10 code fixing the ring at runtime.
  11
  12 Signed-off-by: Sean Wang <keyhaede@gmail.com>
  13 Signed-off-by: John Crispin <john@phrozen.org>
  14 ---
  15  drivers/net/ethernet/mediatek/mtk_eth_soc.c |    3 +--
  16  1 file changed, 1 insertion(+), 2 deletions(-)
  17
  18 diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  19 index 52cdb3a..87b48c0 100644
  20 --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  21 +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  22 @@ -934,7 +934,6 @@ static int mtk_poll_tx(struct mtk_eth *eth, int budget, bool *tx_again)
  23                 }
  24                 mtk_tx_unmap(eth->dev, tx_buf);
  25
  26 -               ring->last_free->txd2 = next_cpu;
  27                 ring->last_free = desc;
  28                 atomic_inc(&ring->free_count);
  29
  30 @@ -1042,7 +1041,7 @@ static int mtk_tx_alloc(struct mtk_eth *eth)
  31
  32         atomic_set(&ring->free_count, MTK_DMA_SIZE - 2);
  33         ring->next_free = &ring->dma[0];
  34 -       ring->last_free = &ring->dma[MTK_DMA_SIZE - 2];
  35 +       ring->last_free = &ring->dma[MTK_DMA_SIZE - 1];
  36         ring->thresh = MAX_SKB_FRAGS;
  37
  38         /* make sure that all changes to the dma ring are flushed before we
  39 --
  40 1.7.10.4
  41