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

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Date:   Fri, 22 Feb 2019 13:44:18 -0800
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Eli Britstein <elibr@...lanox.com>,
        Oz Shlomo <ozsh@...lanox.com>, Roi Dayan <roid@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net-next 1/9] net/mlx5: Use read-modify-write when changing PCMR register values

From: Eli Britstein <elibr@...lanox.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 <elibr@...lanox.com>
Reviewed-by: Oz Shlomo <ozsh@...lanox.com>
Reviewed-by: Roi Dayan <roid@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.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