target/linux/bcm4908/patches-5.4/073-v5.12-0009-net-broadcom-bcm4908_enet-set-MTU-on-open-on-request.patch

   1 From 14b3b46a67f78ade99eafcbf320105615e948569 Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
   3 Date: Fri, 12 Feb 2021 16:21:35 +0100
   4 Subject: [PATCH] net: broadcom: bcm4908_enet: set MTU on open & on request
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 Hardware comes up with default max frame size set to 1518. When using it
  10 with switch it results in actual Ethernet MTU 1492:
  11 1518 - 14 (Ethernet header) - 4 (Broadcom's tag) - 4 (802.1q) - 4 (FCS)
  12
  13 Above means hardware in its default state can't handle standard Ethernet
  14 traffic (MTU 1500).
  15
  16 Define maximum possible Ethernet overhead and always set MAC max frame
  17 length accordingly. This change fixes handling Ethernet frames of length
  18 1506 - 1514.
  19
  20 Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
  21 Signed-off-by: David S. Miller <davem@davemloft.net>
  22 ---
  23  drivers/net/ethernet/broadcom/bcm4908_enet.c | 31 ++++++++++++++++----
  24  1 file changed, 25 insertions(+), 6 deletions(-)
  25
  26 --- a/drivers/net/ethernet/broadcom/bcm4908_enet.c
  27 +++ b/drivers/net/ethernet/broadcom/bcm4908_enet.c
  28 @@ -5,6 +5,7 @@
  29
  30  #include <linux/delay.h>
  31  #include <linux/etherdevice.h>
  32 +#include <linux/if_vlan.h>
  33  #include <linux/interrupt.h>
  34  #include <linux/module.h>
  35  #include <linux/of.h>
  36 @@ -29,9 +30,10 @@
  37                                                  ENET_DMA_CH_CFG_INT_BUFF_DONE)
  38  #define ENET_DMA_MAX_BURST_LEN                 8 /* in 64 bit words */
  39
  40 -#define ENET_MTU_MIN                           60
  41 -#define ENET_MTU_MAX                           1500 /* Is it possible to support 2044? */
  42 -#define ENET_MTU_MAX_EXTRA_SIZE                        32 /* L2 */
  43 +#define ENET_MTU_MAX                           ETH_DATA_LEN /* Is it possible to support 2044? */
  44 +#define BRCM_MAX_TAG_LEN                       6
  45 +#define ENET_MAX_ETH_OVERHEAD                  (ETH_HLEN + BRCM_MAX_TAG_LEN + VLAN_HLEN + \
  46 +                                                ETH_FCS_LEN + 4) /* 32 */
  47
  48  struct bcm4908_enet_dma_ring_bd {
  49         __le32 ctl;
  50 @@ -135,6 +137,11 @@ static void bcm4908_enet_intrs_ack(struc
  51         enet_write(enet, ENET_DMA_CH_RX_CFG + ENET_DMA_CH_CFG_INT_STAT, ENET_DMA_INT_DEFAULTS);
  52  }
  53
  54 +static void bcm4908_enet_set_mtu(struct bcm4908_enet *enet, int mtu)
  55 +{
  56 +       enet_umac_write(enet, UMAC_MAX_FRAME_LEN, mtu + ENET_MAX_ETH_OVERHEAD);
  57 +}
  58 +
  59  /***
  60   * DMA
  61   */
  62 @@ -246,7 +253,7 @@ static int bcm4908_enet_dma_alloc_rx_buf
  63         u32 tmp;
  64         int err;
  65
  66 -       slot->len = ENET_MTU_MAX + ENET_MTU_MAX_EXTRA_SIZE;
  67 +       slot->len = ENET_MTU_MAX + ENET_MAX_ETH_OVERHEAD;
  68
  69         slot->skb = netdev_alloc_skb(enet->netdev, slot->len);
  70         if (!slot->skb)
  71 @@ -374,6 +381,8 @@ static void bcm4908_enet_gmac_init(struc
  72  {
  73         u32 cmd;
  74
  75 +       bcm4908_enet_set_mtu(enet, enet->netdev->mtu);
  76 +
  77         cmd = enet_umac_read(enet, UMAC_CMD);
  78         enet_umac_write(enet, UMAC_CMD, cmd | CMD_SW_RESET);
  79         enet_umac_write(enet, UMAC_CMD, cmd & ~CMD_SW_RESET);
  80 @@ -559,7 +568,7 @@ static int bcm4908_enet_poll(struct napi
  81
  82                 len = (ctl & DMA_CTL_LEN_DESC_BUFLENGTH) >> DMA_CTL_LEN_DESC_BUFLENGTH_SHIFT;
  83
  84 -               if (len < ENET_MTU_MIN ||
  85 +               if (len < ETH_ZLEN ||
  86                     (ctl & (DMA_CTL_STATUS_SOP | DMA_CTL_STATUS_EOP)) != (DMA_CTL_STATUS_SOP | DMA_CTL_STATUS_EOP)) {
  87                         enet->netdev->stats.rx_dropped++;
  88                         break;
  89 @@ -583,11 +592,21 @@ static int bcm4908_enet_poll(struct napi
  90         return handled;
  91  }
  92
  93 +static int bcm4908_enet_change_mtu(struct net_device *netdev, int new_mtu)
  94 +{
  95 +       struct bcm4908_enet *enet = netdev_priv(netdev);
  96 +
  97 +       bcm4908_enet_set_mtu(enet, new_mtu);
  98 +
  99 +       return 0;
 100 +}
 101 +
 102  static const struct net_device_ops bcm4908_enet_netdev_ops = {
 103         .ndo_open = bcm4908_enet_open,
 104         .ndo_stop = bcm4908_enet_stop,
 105         .ndo_start_xmit = bcm4908_enet_start_xmit,
 106         .ndo_set_mac_address = eth_mac_addr,
 107 +       .ndo_change_mtu = bcm4908_enet_change_mtu,
 108  };
 109
 110  static int bcm4908_enet_probe(struct platform_device *pdev)
 111 @@ -625,7 +644,7 @@ static int bcm4908_enet_probe(struct pla
 112         eth_hw_addr_random(netdev);
 113         netdev->netdev_ops = &bcm4908_enet_netdev_ops;
 114         netdev->min_mtu = ETH_ZLEN;
 115 -       netdev->mtu = ENET_MTU_MAX;
 116 +       netdev->mtu = ETH_DATA_LEN;
 117         netdev->max_mtu = ENET_MTU_MAX;
 118         netif_napi_add(netdev, &enet->napi, bcm4908_enet_poll, 64);
 119