IB/mlx5: Add port_xmit_wait to counter registers read

Add port_xmit_wait to the error counters read by mlx5_ib_process_mad to
ensure sysfs port counter provides correct value for PortXmitWait.
Otherwise the sysfs port_xmit_wait file always contains zero.

The previous MAD_IFC implementation populated this counter, but it was
removed during the migration to PPCNT for error counters (32-bit only).
Signed-off-by: Tim Wright <tim@binbash.co.uk>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/mad.c

@@ -187,6 +187,8 @@ static void pma_cnt_assign(struct ib_pma_portcounters *pma_cnt,
 			     port_xmit_discards);
 	MLX5_ASSIGN_PMA_CNTR(pma_cnt->port_xmit_constraint_errors,
 			     port_xmit_constraint_errors);
+	MLX5_ASSIGN_PMA_CNTR(pma_cnt->port_xmit_wait,
+			     port_xmit_wait);
 	MLX5_ASSIGN_PMA_CNTR(pma_cnt->port_rcv_constraint_errors,
 			     port_rcv_constraint_errors);
 	MLX5_ASSIGN_PMA_CNTR(pma_cnt->link_overrun_errors,

include/linux/mlx5/mlx5_ifc.h

@@ -1456,7 +1456,9 @@ struct mlx5_ifc_ib_port_cntrs_grp_data_layout_bits {
 
 	u8         vl_15_dropped[0x10];
 
-	u8	   reserved_at_a0[0xa0];
+	u8	   reserved_at_a0[0x80];
+
+	u8         port_xmit_wait[0x20];
 };
 
 struct mlx5_ifc_eth_per_traffic_grp_data_layout_bits {