[PATCH net] mlxsw: spectrum: Adjust headroom buffers for 8x ports

[Ido Schimmel <idosch@idosch.org>]

From: Ido Schimmel <idosch@mellanox.com>

The port's headroom buffers are used to store packets while they
traverse the device's pipeline and also to store packets that are egress
mirrored.

On Spectrum-3, ports with eight lanes use two headroom buffers between
which the configured headroom size is split.

In order to prevent packet loss, multiply the calculated headroom size
by two for 8x ports.

Fixes: da382875c616 ("mlxsw: spectrum: Extend to support Spectrum-3 ASIC")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c      |  2 ++
 drivers/net/ethernet/mellanox/mlxsw/spectrum.h      | 13 +++++++++++++
 .../net/ethernet/mellanox/mlxsw/spectrum_buffers.c  |  1 +
 drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c |  1 +
 4 files changed, 17 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index 5ffa32b75e5f..55af877763ed 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -978,8 +978,10 @@ int __mlxsw_sp_port_headroom_set(struct mlxsw_sp_port *mlxsw_sp_port, int mtu,
 
 		lossy = !(pfc || pause_en);
 		thres_cells = mlxsw_sp_pg_buf_threshold_get(mlxsw_sp, mtu);
+		mlxsw_sp_port_headroom_8x_adjust(mlxsw_sp_port, &thres_cells);
 		delay_cells = mlxsw_sp_pg_buf_delay_get(mlxsw_sp, mtu, delay,
 							pfc, pause_en);
+		mlxsw_sp_port_headroom_8x_adjust(mlxsw_sp_port, &delay_cells);
 		total_cells = thres_cells + delay_cells;
 
 		taken_headroom_cells += total_cells;
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.h b/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
index 6f96ca50c9ba..6e87457dd635 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
@@ -374,6 +374,19 @@ mlxsw_sp_port_vlan_find_by_vid(const struct mlxsw_sp_port *mlxsw_sp_port,
 	return NULL;
 }
 
+static inline void
+mlxsw_sp_port_headroom_8x_adjust(const struct mlxsw_sp_port *mlxsw_sp_port,
+				 u16 *p_size)
+{
+	/* Ports with eight lanes use two headroom buffers between which the
+	 * configured headroom size is split. Therefore, multiply the calculated
+	 * headroom size by two.
+	 */
+	if (mlxsw_sp_port->mapping.width != 8)
+		return;
+	*p_size *= 2;
+}
+
 enum mlxsw_sp_flood_type {
 	MLXSW_SP_FLOOD_TYPE_UC,
 	MLXSW_SP_FLOOD_TYPE_BC,
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
index 21bfb2f6a6f0..f25a8b084b4b 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
@@ -312,6 +312,7 @@ static int mlxsw_sp_port_pb_init(struct mlxsw_sp_port *mlxsw_sp_port)
 
 		if (i == MLXSW_SP_PB_UNUSED)
 			continue;
+		mlxsw_sp_port_headroom_8x_adjust(mlxsw_sp_port, &size);
 		mlxsw_reg_pbmc_lossy_buffer_pack(pbmc_pl, i, size);
 	}
 	mlxsw_reg_pbmc_lossy_buffer_pack(pbmc_pl,
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
index 304eb8c3d8bd..f843545d3478 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c
@@ -782,6 +782,7 @@ mlxsw_sp_span_port_buffer_update(struct mlxsw_sp_port *mlxsw_sp_port, u16 mtu)
 		speed = 0;
 
 	buffsize = mlxsw_sp_span_buffsize_get(mlxsw_sp, speed, mtu);
+	mlxsw_sp_port_headroom_8x_adjust(mlxsw_sp_port, (u16 *) &buffsize);
 	mlxsw_reg_sbib_pack(sbib_pl, mlxsw_sp_port->local_port, buffsize);
 	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(sbib), sbib_pl);
 }
-- 
2.26.2