target/linux/generic/backport-5.15/775-v6.0-05-net-ethernet-stmicro-stmmac-permit-MTU-change-with-i.patch

   1 From 3470079687448abac42deb62774253be1d6bdef3 Mon Sep 17 00:00:00 2001
   2 From: Christian Marangi <ansuelsmth@gmail.com>
   3 Date: Sat, 23 Jul 2022 16:29:33 +0200
   4 Subject: [PATCH 5/5] net: ethernet: stmicro: stmmac: permit MTU change with
   5  interface up
   6
   7 Remove the limitation where the interface needs to be down to change
   8 MTU by releasing and opening the stmmac driver to set the new MTU.
   9 Also call the set_filter function to correctly init the port.
  10 This permits to remove the EBUSY error while the ethernet port is
  11 running permitting a correct MTU change if for example a DSA request
  12 a MTU change for a switch CPU port.
  13
  14 Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
  15 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
  16 ---
  17  .../net/ethernet/stmicro/stmmac/stmmac_main.c | 30 +++++++++++++++----
  18  1 file changed, 24 insertions(+), 6 deletions(-)
  19
  20 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
  21 +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
  22 @@ -5624,18 +5624,15 @@ static int stmmac_change_mtu(struct net_
  23  {
  24         struct stmmac_priv *priv = netdev_priv(dev);
  25         int txfifosz = priv->plat->tx_fifo_size;
  26 +       struct stmmac_dma_conf *dma_conf;
  27         const int mtu = new_mtu;
  28 +       int ret;
  29
  30         if (txfifosz == 0)
  31                 txfifosz = priv->dma_cap.tx_fifo_size;
  32
  33         txfifosz /= priv->plat->tx_queues_to_use;
  34
  35 -       if (netif_running(dev)) {
  36 -               netdev_err(priv->dev, "must be stopped to change its MTU\n");
  37 -               return -EBUSY;
  38 -       }
  39 -
  40         if (stmmac_xdp_is_enabled(priv) && new_mtu > ETH_DATA_LEN) {
  41                 netdev_dbg(priv->dev, "Jumbo frames not supported for XDP\n");
  42                 return -EINVAL;
  43 @@ -5647,8 +5644,29 @@ static int stmmac_change_mtu(struct net_
  44         if ((txfifosz < new_mtu) || (new_mtu > BUF_SIZE_16KiB))
  45                 return -EINVAL;
  46
  47 -       dev->mtu = mtu;
  48 +       if (netif_running(dev)) {
  49 +               netdev_dbg(priv->dev, "restarting interface to change its MTU\n");
  50 +               /* Try to allocate the new DMA conf with the new mtu */
  51 +               dma_conf = stmmac_setup_dma_desc(priv, mtu);
  52 +               if (IS_ERR(dma_conf)) {
  53 +                       netdev_err(priv->dev, "failed allocating new dma conf for new MTU %d\n",
  54 +                                  mtu);
  55 +                       return PTR_ERR(dma_conf);
  56 +               }
  57 +
  58 +               stmmac_release(dev);
  59 +
  60 +               ret = __stmmac_open(dev, dma_conf);
  61 +               kfree(dma_conf);
  62 +               if (ret) {
  63 +                       netdev_err(priv->dev, "failed reopening the interface after MTU change\n");
  64 +                       return ret;
  65 +               }
  66 +
  67 +               stmmac_set_rx_mode(dev);
  68 +       }
  69
  70 +       dev->mtu = mtu;
  71         netdev_update_features(dev);
  72
  73         return 0;