target/linux/generic/backport-5.10/610-v5.13-46-net-ethernet-mtk_eth_soc-cache-HW-pointer-of-last-fr.patch

   1 From 4e6bf609569c59b6bd6acf4a607c096cbd820d79 Mon Sep 17 00:00:00 2001
   2 From: Felix Fietkau <nbd@nbd.name>
   3 Date: Thu, 22 Apr 2021 22:21:03 -0700
   4 Subject: [PATCH] net: ethernet: mtk_eth_soc: cache HW pointer of last freed TX
   5  descriptor
   6
   7 The value is only updated by the CPU, so it is cheaper to access from the
   8 ring data structure than from a hardware register.
   9
  10 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  11 Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
  12 Signed-off-by: David S. Miller <davem@davemloft.net>
  13 ---
  14  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 8 ++++----
  15  drivers/net/ethernet/mediatek/mtk_eth_soc.h | 2 ++
  16  2 files changed, 6 insertions(+), 4 deletions(-)
  17
  18 --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  19 +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
  20 @@ -1399,7 +1399,7 @@ static int mtk_poll_tx_qdma(struct mtk_e
  21         struct mtk_tx_buf *tx_buf;
  22         u32 cpu, dma;
  23
  24 -       cpu = mtk_r32(eth, MTK_QTX_CRX_PTR);
  25 +       cpu = ring->last_free_ptr;
  26         dma = mtk_r32(eth, MTK_QTX_DRX_PTR);
  27
  28         desc = mtk_qdma_phys_to_virt(ring, cpu);
  29 @@ -1433,6 +1433,7 @@ static int mtk_poll_tx_qdma(struct mtk_e
  30                 cpu = next_cpu;
  31         }
  32
  33 +       ring->last_free_ptr = cpu;
  34         mtk_w32(eth, cpu, MTK_QTX_CRX_PTR);
  35
  36         return budget;
  37 @@ -1633,6 +1634,7 @@ static int mtk_tx_alloc(struct mtk_eth *
  38         atomic_set(&ring->free_count, MTK_DMA_SIZE - 2);
  39         ring->next_free = &ring->dma[0];
  40         ring->last_free = &ring->dma[MTK_DMA_SIZE - 1];
  41 +       ring->last_free_ptr = (u32)(ring->phys + ((MTK_DMA_SIZE - 1) * sz));
  42         ring->thresh = MAX_SKB_FRAGS;
  43
  44         /* make sure that all changes to the dma ring are flushed before we
  45 @@ -1646,9 +1648,7 @@ static int mtk_tx_alloc(struct mtk_eth *
  46                 mtk_w32(eth,
  47                         ring->phys + ((MTK_DMA_SIZE - 1) * sz),
  48                         MTK_QTX_CRX_PTR);
  49 -               mtk_w32(eth,
  50 -                       ring->phys + ((MTK_DMA_SIZE - 1) * sz),
  51 -                       MTK_QTX_DRX_PTR);
  52 +               mtk_w32(eth, ring->last_free_ptr, MTK_QTX_DRX_PTR);
  53                 mtk_w32(eth, (QDMA_RES_THRES << 8) | QDMA_RES_THRES,
  54                         MTK_QTX_CFG(0));
  55         } else {
  56 --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
  57 +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
  58 @@ -656,6 +656,7 @@ struct mtk_tx_buf {
  59   * @phys:              The physical addr of tx_buf
  60   * @next_free:         Pointer to the next free descriptor
  61   * @last_free:         Pointer to the last free descriptor
  62 + * @last_free_ptr:     Hardware pointer value of the last free descriptor
  63   * @thresh:            The threshold of minimum amount of free descriptors
  64   * @free_count:                QDMA uses a linked list. Track how many free descriptors
  65   *                     are present
  66 @@ -666,6 +667,7 @@ struct mtk_tx_ring {
  67         dma_addr_t phys;
  68         struct mtk_tx_dma *next_free;
  69         struct mtk_tx_dma *last_free;
  70 +       u32 last_free_ptr;
  71         u16 thresh;
  72         atomic_t free_count;
  73         int dma_size;