mlxsw: Remove 56G speed support

Commit 275e928f ("mlxsw: spectrum: Prevent force of 56G") prevented
the driver from setting a speed of 56G when auto-negotiation is off.
This is the only speed supported by mlxsw that cannot be set when
auto-negotiation is off, which makes it difficult to write generic
tests.

Further, the speed is not supported by newer ASICs such as Spectrum-2
and to the best of our knowledge it is not used by current users.

Therefore, remove 56G support from mlxsw.
Signed-off-by: Amit Cohen <amitc@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/reg.h

@@ -4126,7 +4126,6 @@ MLXSW_ITEM32(reg, ptys, ext_eth_proto_cap, 0x08, 0, 32);
 #define MLXSW_REG_PTYS_ETH_SPEED_20GBASE_KR2		BIT(5)
 #define MLXSW_REG_PTYS_ETH_SPEED_40GBASE_CR4		BIT(6)
 #define MLXSW_REG_PTYS_ETH_SPEED_40GBASE_KR4		BIT(7)
-#define MLXSW_REG_PTYS_ETH_SPEED_56GBASE_R4		BIT(8)
 #define MLXSW_REG_PTYS_ETH_SPEED_10GBASE_CR		BIT(12)
 #define MLXSW_REG_PTYS_ETH_SPEED_10GBASE_SR		BIT(13)
 #define MLXSW_REG_PTYS_ETH_SPEED_10GBASE_ER_LR		BIT(14)

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -2608,26 +2608,6 @@ static const struct mlxsw_sp1_port_link_mode mlxsw_sp1_port_link_mode[] = {
 		.mask_ethtool	= ETHTOOL_LINK_MODE_50000baseSR2_Full_BIT,
 		.speed		= SPEED_50000,
 	},
-	{
-		.mask		= MLXSW_REG_PTYS_ETH_SPEED_56GBASE_R4,
-		.mask_ethtool	= ETHTOOL_LINK_MODE_56000baseKR4_Full_BIT,
-		.speed		= SPEED_56000,
-	},
-	{
-		.mask		= MLXSW_REG_PTYS_ETH_SPEED_56GBASE_R4,
-		.mask_ethtool	= ETHTOOL_LINK_MODE_56000baseCR4_Full_BIT,
-		.speed		= SPEED_56000,
-	},
-	{
-		.mask		= MLXSW_REG_PTYS_ETH_SPEED_56GBASE_R4,
-		.mask_ethtool	= ETHTOOL_LINK_MODE_56000baseSR4_Full_BIT,
-		.speed		= SPEED_56000,
-	},
-	{
-		.mask		= MLXSW_REG_PTYS_ETH_SPEED_56GBASE_R4,
-		.mask_ethtool	= ETHTOOL_LINK_MODE_56000baseLR4_Full_BIT,
-		.speed		= SPEED_56000,
-	},
 	{
 		.mask		= MLXSW_REG_PTYS_ETH_SPEED_100GBASE_CR4,
 		.mask_ethtool	= ETHTOOL_LINK_MODE_100000baseCR4_Full_BIT,
@@ -3301,10 +3281,6 @@ mlxsw_sp_port_set_link_ksettings(struct net_device *dev,
 	ops->reg_ptys_eth_unpack(mlxsw_sp, ptys_pl, &eth_proto_cap, NULL, NULL);
 
 	autoneg = cmd->base.autoneg == AUTONEG_ENABLE;
-	if (!autoneg && cmd->base.speed == SPEED_56000) {
-		netdev_err(dev, "56G not supported with autoneg off\n");
-		return -EINVAL;
-	}
 	eth_proto_new = autoneg ?
 		ops->to_ptys_advert_link(mlxsw_sp, cmd) :
 		ops->to_ptys_speed(mlxsw_sp, cmd->base.speed);

drivers/net/ethernet/mellanox/mlxsw/switchx2.c

@@ -636,12 +636,6 @@ static const struct mlxsw_sx_port_link_mode mlxsw_sx_port_link_mode[] = {
 				  MLXSW_REG_PTYS_ETH_SPEED_50GBASE_KR2,
 		.speed		= 50000,
 	},
-	{
-		.mask		= MLXSW_REG_PTYS_ETH_SPEED_56GBASE_R4,
-		.supported	= SUPPORTED_56000baseKR4_Full,
-		.advertised	= ADVERTISED_56000baseKR4_Full,
-		.speed		= 56000,
-	},
 	{
 		.mask		= MLXSW_REG_PTYS_ETH_SPEED_100GBASE_CR4 |
 				  MLXSW_REG_PTYS_ETH_SPEED_100GBASE_SR4 |