net/mlx5: do not select legacy MPW implicitly

The Legacy MPW (multi-packet write) should not be engaged implicitly.
We should exclude this function from a Tx burst routine selection
process unless it is requested specifically by setting the txq_mpw_en
devarg.  Exclude this function from the selection process the same way
it is done for the Enhanced MPW in the mlx5_select_tx_function()
routine.

Fixes: eb8121ab9dac ("net/mlx5: introduce Tx burst routine template")
Cc: stable@dpdk.org
Signed-off-by: Alexander Kozyrev <akozyrev@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>

diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 22cdf15..4d67925 100644 (file)
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -5542,6 +5542,9 @@ mlx5_select_tx_function(struct rte_eth_dev *dev)
                        /* Does not meet requested offloads at all. */
                        continue;
                }
+               if ((olx ^ tmp) & MLX5_TXOFF_CONFIG_MPW)
+                       /* Do not enable legacy MPW if not configured. */
+                       continue;
                if ((olx ^ tmp) & MLX5_TXOFF_CONFIG_EMPW)
                        /* Do not enable eMPW if not configured. */
                        continue;