Re: [PATCH net v1] mlxbf_gige: disable port during stop()

From: Benjamin Poirier
Date: Mon Aug 19 2024 - 14:55:25 EST


On 2024-08-16 16:48 -0400, David Thompson wrote:
> The mlxbf_gige_open() routine initializes and enables the
> Gigabit Ethernet port from a hardware point of view. The
> mlxbf_gige_stop() routine must disable the port hardware
> to fully quiesce it.
>
> Fixes: f92e1869d74e ("Add Mellanox BlueField Gigabit Ethernet driver")
> Reviewed-by: Asmaa Mnebhi <asmaa@xxxxxxxxxx>
> Signed-off-by: David Thompson <davthompson@xxxxxxxxxx>
> ---
> drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c
> index 385a56ac7348..12942a50e1bb 100644
> --- a/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c
> +++ b/drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c
> @@ -205,8 +205,14 @@ static int mlxbf_gige_open(struct net_device *netdev)
> static int mlxbf_gige_stop(struct net_device *netdev)
> {
> struct mlxbf_gige *priv = netdev_priv(netdev);
> + u64 control;
> +
> + control = readq(priv->base + MLXBF_GIGE_CONTROL);
> + control &= ~MLXBF_GIGE_CONTROL_PORT_EN;
> + writeq(control, priv->base + MLXBF_GIGE_CONTROL);
>
> writeq(0, priv->base + MLXBF_GIGE_INT_EN);
> + mb();

checkpatch says:
WARNING: memory barrier without comment
#37: FILE: drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_main.c:215:
+ mb();

Is this memory barrier paired with another one?