[PATCH AUTOSEL 4.9 20/20] mlxsw: spectrum: Prevent force of 56G

[Sasha Levin <sashal@xxxxxxxxxx>]

From: Amit Cohen <amitc@xxxxxxxxxxxx>

[ Upstream commit 275e928f19117d22f6d26dee94548baf4041b773 ]

Force of 56G is not supported by hardware in Ethernet devices. This
configuration fails with a bad parameter error from firmware.

Add check of this case. Instead of trying to set 56G with autoneg off,
return a meaningful error.

Fixes: 56ade8fe3fe1 ("mlxsw: spectrum: Add initial support for Spectrum ASIC")
Signed-off-by: Amit Cohen <amitc@xxxxxxxxxxxx>
Acked-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index e3ed70a24029..585a40cc6470 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -2044,6 +2044,10 @@ mlxsw_sp_port_set_link_ksettings(struct net_device *dev,
 	mlxsw_reg_ptys_unpack(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 ?
 		mlxsw_sp_to_ptys_advert_link(cmd) :
 		mlxsw_sp_to_ptys_speed(cmd->base.speed);
-- 
2.20.1