[net-next 1/9] net/mlx5: Use read-modify-write when changing PCMR register values

[Saeed Mahameed]

From: Eli Britstein <el...@mellanox.com>

Currently changing a PCMR field is done by setting the field in a
zeroed buffer, zeroing other unrelated fields.
Fix this behaviour by modifying only the required field after first
reading the current register values, as a pre-step towards using more
fields in PCMR register.

Signed-off-by: Eli Britstein <el...@mellanox.com>
Reviewed-by: Oz Shlomo <o...@mellanox.com>
Reviewed-by: Roi Dayan <r...@mellanox.com>
Signed-off-by: Saeed Mahameed <sae...@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/port.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/port.c 
b/drivers/net/ethernet/mellanox/mlx5/core/port.c
index b81542820528..55b30d21a73a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/port.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/port.c
@@ -785,7 +785,11 @@ static int mlx5_set_ports_check(struct mlx5_core_dev 
*mdev, u32 *in, int inlen)
 int mlx5_set_port_fcs(struct mlx5_core_dev *mdev, u8 enable)
 {
        u32 in[MLX5_ST_SZ_DW(pcmr_reg)] = {0};
+       int err;
 
+       err = mlx5_query_ports_check(mdev, in, sizeof(in));
+       if (err)
+               return err;
        MLX5_SET(pcmr_reg, in, local_port, 1);
        MLX5_SET(pcmr_reg, in, fcs_chk, enable);
        return mlx5_set_ports_check(mdev, in, sizeof(in));
-- 
2.20.1