mlxsw: spectrum_qdisc: Disable port buffer autoresize with qdiscs

There are two interfaces to configure ETS: qdiscs and DCB. Historically,
DCB ETS configuration was projected to ingress as well, and configured port
buffers. Qdisc was not.

Keep qdiscs behaving this way, and if an offloaded qdisc is configured on a
port, move this port's headroom to a manual mode, thus allowing
configuration of port buffers through dcbnl_setbuffer.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -140,18 +140,31 @@ static int
 mlxsw_sp_qdisc_destroy(struct mlxsw_sp_port *mlxsw_sp_port,
 		       struct mlxsw_sp_qdisc *mlxsw_sp_qdisc)
 {
+	struct mlxsw_sp_qdisc *root_qdisc = &mlxsw_sp_port->qdisc->root_qdisc;
+	int err_hdroom = 0;
 	int err = 0;
 
 	if (!mlxsw_sp_qdisc)
 		return 0;
 
+	if (root_qdisc == mlxsw_sp_qdisc) {
+		struct mlxsw_sp_hdroom hdroom = *mlxsw_sp_port->hdroom;
+
+		hdroom.mode = MLXSW_SP_HDROOM_MODE_DCB;
+		mlxsw_sp_hdroom_prios_reset_buf_idx(&hdroom);
+		mlxsw_sp_hdroom_bufs_reset_lossiness(&hdroom);
+		mlxsw_sp_hdroom_bufs_reset_sizes(mlxsw_sp_port, &hdroom);
+		err_hdroom = mlxsw_sp_hdroom_configure(mlxsw_sp_port, &hdroom);
+	}
+
 	if (mlxsw_sp_qdisc->ops && mlxsw_sp_qdisc->ops->destroy)
 		err = mlxsw_sp_qdisc->ops->destroy(mlxsw_sp_port,
 						   mlxsw_sp_qdisc);
 
 	mlxsw_sp_qdisc->handle = TC_H_UNSPEC;
 	mlxsw_sp_qdisc->ops = NULL;
-	return err;
+
+	return err_hdroom ?: err;
 }
 
 static int
@@ -159,6 +172,8 @@ mlxsw_sp_qdisc_replace(struct mlxsw_sp_port *mlxsw_sp_port, u32 handle,
 		       struct mlxsw_sp_qdisc *mlxsw_sp_qdisc,
 		       struct mlxsw_sp_qdisc_ops *ops, void *params)
 {
+	struct mlxsw_sp_qdisc *root_qdisc = &mlxsw_sp_port->qdisc->root_qdisc;
+	struct mlxsw_sp_hdroom orig_hdroom;
 	int err;
 
 	if (mlxsw_sp_qdisc->ops && mlxsw_sp_qdisc->ops->type != ops->type)
@@ -168,6 +183,21 @@ mlxsw_sp_qdisc_replace(struct mlxsw_sp_port *mlxsw_sp_port, u32 handle,
 		 * new one.
 		 */
 		mlxsw_sp_qdisc_destroy(mlxsw_sp_port, mlxsw_sp_qdisc);
+
+	orig_hdroom = *mlxsw_sp_port->hdroom;
+	if (root_qdisc == mlxsw_sp_qdisc) {
+		struct mlxsw_sp_hdroom hdroom = orig_hdroom;
+
+		hdroom.mode = MLXSW_SP_HDROOM_MODE_TC;
+		mlxsw_sp_hdroom_prios_reset_buf_idx(&hdroom);
+		mlxsw_sp_hdroom_bufs_reset_lossiness(&hdroom);
+		mlxsw_sp_hdroom_bufs_reset_sizes(mlxsw_sp_port, &hdroom);
+
+		err = mlxsw_sp_hdroom_configure(mlxsw_sp_port, &hdroom);
+		if (err)
+			goto err_hdroom_configure;
+	}
+
 	err = ops->check_params(mlxsw_sp_port, mlxsw_sp_qdisc, params);
 	if (err)
 		goto err_bad_param;
@@ -191,6 +221,8 @@ mlxsw_sp_qdisc_replace(struct mlxsw_sp_port *mlxsw_sp_port, u32 handle,
 
 err_bad_param:
 err_config:
+	mlxsw_sp_hdroom_configure(mlxsw_sp_port, &orig_hdroom);
+err_hdroom_configure:
 	if (mlxsw_sp_qdisc->handle == handle && ops->unoffload)
 		ops->unoffload(mlxsw_sp_port, mlxsw_sp_qdisc, params);