net/mlx5e: Fix minimum MTU

Minimum MTU that can be set in Connectx4 device is 68.

This fixes the case where a user wants to set invalid MTU,
the driver will fail to satisfy this request and the interface
will stay down.

It is better to report an error and continue working with old
mtu.

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 2fbbc625f106f3aa5125069eadf2c1802719141d..93e4ef43fa9f12daebf09527899f3ccd6f5609ab 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -1999,22 +1999,27 @@ static int mlx5e_set_features(struct net_device *netdev,
        return err;
 }
 
+#define MXL5_HW_MIN_MTU 64
+#define MXL5E_MIN_MTU (MXL5_HW_MIN_MTU + ETH_FCS_LEN)
+
 static int mlx5e_change_mtu(struct net_device *netdev, int new_mtu)
 {
        struct mlx5e_priv *priv = netdev_priv(netdev);
        struct mlx5_core_dev *mdev = priv->mdev;
        bool was_opened;
        u16 max_mtu;
+       u16 min_mtu;
        int err = 0;
 
        mlx5_query_port_max_mtu(mdev, &max_mtu, 1);
 
        max_mtu = MLX5E_HW2SW_MTU(max_mtu);
+       min_mtu = MLX5E_HW2SW_MTU(MXL5E_MIN_MTU);
 
-       if (new_mtu > max_mtu) {
+       if (new_mtu > max_mtu || new_mtu < min_mtu) {
                netdev_err(netdev,
-                          "%s: Bad MTU (%d) > (%d) Max\n",
-                          __func__, new_mtu, max_mtu);
+                          "%s: Bad MTU (%d), valid range is: [%d..%d]\n",
+                          __func__, new_mtu, min_mtu, max_mtu);
                return -EINVAL;
        }