net/mlx5e: ethtool, Avoid setting speed to 56GBASE when autoneg off

Setting speed to 56GBASE is allowed only with auto-negotiation enabled.

This patch prevent setting speed to 56GBASE when auto-negotiation disabled.

Fixes: f62b8bb8 ("net/mlx5: Extend mlx5_core to support ConnectX-4 Ethernet functionality")
Signed-off-by: Mohamad Heib <mohamadh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c

@@ -1081,6 +1081,14 @@ int mlx5e_ethtool_set_link_ksettings(struct mlx5e_priv *priv,
 	link_modes = autoneg == AUTONEG_ENABLE ? ethtool2ptys_adver_func(adver) :
 		mlx5e_port_speed2linkmodes(mdev, speed, !ext);
 
+	if ((link_modes & MLX5E_PROT_MASK(MLX5E_56GBASE_R4)) &&
+	    autoneg != AUTONEG_ENABLE) {
+		netdev_err(priv->netdev, "%s: 56G link speed requires autoneg enabled\n",
+			   __func__);
+		err = -EINVAL;
+		goto out;
+	}
+
 	link_modes = link_modes & eproto.cap;
 	if (!link_modes) {
 		netdev_err(priv->netdev, "%s: Not supported link mode(s) requested",