[PATCH net-next mlxsw 3/3] mlxsw: spectrum: Configure MC-aware mode on mlxsw ports

[Petr Machata]

In order to give unicast traffic precedence over BUM traffic, configure
multicast-aware mode on all ports.

Under multicast-aware regime, when assigning traffic class to a packet,
the switch doesn't merely take the value prescribed by the QTCT
register. For BUM traffic, it instead assigns that value plus 8.

ETS elements for TCs 8..15 thus need to be configured as well. Extend
mlxsw_sp_port_ets_init() so that it maps each of them to the same
subgroup as their corresponding TC from the range 0..7, such that TCs X
and X+8 map to the same subgroup.

The existing code configures TCs with strict priority. So far this was
immaterial, because each TC had its own subgroup. Now that two TCs share
a subgroup it becomes important. TCs are prioritized in order of 7, 6,
..., 0, 15, 14, ..., 8: the higher TCs used for BUM traffic end up being
deprioritized. Since that's what's needed, keep that configuration as it
is, and configure the new TCs likewise.

Finally in mlxsw_sp_port_create(), invoke configuration of QTCTM to
enable MC-aware mode on each port.

Signed-off-by: Petr Machata <petrm at mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index 42312ff57b7e..5e2c968f0b70 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -2760,6 +2760,13 @@ static int mlxsw_sp_port_ets_init(struct mlxsw_sp_port *mlxsw_sp_port)
 					    false, 0);
 		if (err)
 			return err;
+
+		err = mlxsw_sp_port_ets_set(mlxsw_sp_port,
+					    MLXSW_REG_QEEC_HIERARCY_TC,
+					    i + 8, i,
+					    false, 0);
+		if (err)
+			return err;
 	}
 
 	/* Make sure the max shaper is disabled in all hierarchies that
@@ -2797,6 +2804,15 @@ static int mlxsw_sp_port_ets_init(struct mlxsw_sp_port *mlxsw_sp_port)
 	return 0;
 }
 
+static int mlxsw_sp_port_tc_mc_mode_set(struct mlxsw_sp_port *mlxsw_sp_port)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	char qtctm_pl[MLXSW_REG_QTCTM_LEN];
+
+	mlxsw_reg_qtctm_pack(qtctm_pl, mlxsw_sp_port->local_port, true);
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(qtctm), qtctm_pl);
+}
+
 static int mlxsw_sp_port_create(struct mlxsw_sp *mlxsw_sp, u8 local_port,
 				bool split, u8 module, u8 width, u8 lane)
 {
@@ -2925,6 +2941,13 @@ static int mlxsw_sp_port_create(struct mlxsw_sp *mlxsw_sp, u8 local_port,
 		goto err_port_ets_init;
 	}
 
+	err = mlxsw_sp_port_tc_mc_mode_set(mlxsw_sp_port);
+	if (err) {
+		dev_err(mlxsw_sp->bus_info->dev, "Port %d: Failed to initialize TC MC mode\n",
+			mlxsw_sp_port->local_port);
+		goto err_port_tc_mc_mode;
+	}
+
 	/* ETS and buffers must be initialized before DCB. */
 	err = mlxsw_sp_port_dcb_init(mlxsw_sp_port);
 	if (err) {
@@ -2981,6 +3004,7 @@ static int mlxsw_sp_port_create(struct mlxsw_sp *mlxsw_sp, u8 local_port,
 err_port_fids_init:
 	mlxsw_sp_port_dcb_fini(mlxsw_sp_port);
 err_port_dcb_init:
+err_port_tc_mc_mode:
 err_port_ets_init:
 err_port_buffers_init:
 err_port_admin_status_set:
-- 
2.4.11