net/mlx5e: Get the latest values from counters in switchdev mode

In the switchdev mode, when running "cat
/sys/class/net/NIC/statistics/tx_packets", the ppcnt register is
accessed to get the latest values. But currently this command can
not get the correct values from ppcnt.

From firmware manual, before getting the 802_3 counters, the 802_3
data layout should be set to the ppcnt register.

When the command "cat /sys/class/net/NIC/statistics/tx_packets" is
run, before updating 802_3 data layout with ppcnt register, the
monitor counters are tested. The test result will decide the
802_3 data layout is updated or not.

Actually the monitor counters do not support to monitor rx/tx
stats of 802_3 in switchdev mode. So the rx/tx counters change
will not trigger monitor counters. So the 802_3 data layout will
not be updated in ppcnt register. Finally this command can not get
the latest values from ppcnt register with 802_3 data layout.

Fixes: 5c7e8bbb02 ("net/mlx5e: Use monitor counters for update stats")
Signed-off-by: Zhu Yanjun <yanjunz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -3583,7 +3583,12 @@ mlx5e_get_stats(struct net_device *dev, struct rtnl_link_stats64 *stats)
 	struct mlx5e_vport_stats *vstats = &priv->stats.vport;
 	struct mlx5e_pport_stats *pstats = &priv->stats.pport;
 
-	if (!mlx5e_monitor_counter_supported(priv)) {
+	/* In switchdev mode, monitor counters doesn't monitor
+	 * rx/tx stats of 802_3. The update stats mechanism
+	 * should keep the 802_3 layout counters updated
+	 */
+	if (!mlx5e_monitor_counter_supported(priv) ||
+	    mlx5e_is_uplink_rep(priv)) {
 		/* update HW stats in background for next time */
 		mlx5e_queue_update_stats(priv);
 	}