netdev - Re: [net-next 03/15] net/mlx5e: PFC stall prevention support

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Date:   Sat, 24 Mar 2018 16:07:09 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Saeed Mahameed <saeedm@...lanox.com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Inbar Karmy <inbark@...lanox.com>
Subject: Re: [net-next 03/15] net/mlx5e: PFC stall prevention support

On Fri, Mar 23, 2018 at 03:39:13PM -0700, Saeed Mahameed wrote:
> From: Inbar Karmy <inbark@...lanox.com>
> 
> Implement set/get functions to configure PFC stall prevention
> timeout by tunables api through ethtool.
> By default the stall prevention timeout is configured to 8 sec.
> Timeout range is: 80-8000 msec.
> Enabling stall prevention without a specific timeout will set
> the timeout to 100 msec.

Hi Inbar

I think this last sentence should be talking about auto, not without a
specific timeout.

> 
> Signed-off-by: Inbar Karmy <inbark@...lanox.com>
> Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
> ---
>  .../net/ethernet/mellanox/mlx5/core/en_ethtool.c   | 57 +++++++++++++++++++
>  drivers/net/ethernet/mellanox/mlx5/core/port.c     | 64 +++++++++++++++++++---
>  include/linux/mlx5/mlx5_ifc.h                      | 17 ++++--
>  include/linux/mlx5/port.h                          |  6 ++
>  4 files changed, 132 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> index cc8048f68f11..62061fd23143 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
> @@ -1066,6 +1066,57 @@ static int mlx5e_get_rxnfc(struct net_device *netdev,
>  	return err;
>  }
>  
> +#define MLX5E_PFC_PREVEN_AUTO_TOUT_MSEC		100
> +#define MLX5E_PFC_PREVEN_TOUT_MAX_MSEC		8000
> +#define MLX5E_PFC_PREVEN_MINOR_PRECENT		85
> +#define MLX5E_PFC_PREVEN_TOUT_MIN_MSEC		80
> +#define MLX5E_DEVICE_STALL_MINOR_WATERMARK(critical_tout) \
> +	max_t(u16, MLX5E_PFC_PREVEN_TOUT_MIN_MSEC, \
> +	      (critical_tout * MLX5E_PFC_PREVEN_MINOR_PRECENT) / 100)
> +
> +static int mlx5e_get_pfc_prevention_tout(struct net_device *netdev,
> +					 u16 *pfc_prevention_tout)
> +{
> +	struct mlx5e_priv *priv    = netdev_priv(netdev);
> +	struct mlx5_core_dev *mdev = priv->mdev;
> +
> +	if (!MLX5_CAP_PCAM_FEATURE((priv)->mdev, pfcc_mask) ||
> +	    !MLX5_CAP_DEBUG((priv)->mdev, stall_detect))
> +		return -EOPNOTSUPP;
> +
> +	return mlx5_query_port_stall_watermark(mdev, pfc_prevention_tout, NULL);

Shouldn't you map a value of MLX5E_PFC_PREVEN_AUTO_TOUT_MSEC back to 
PFC_STORM_PREVENTION_AUTO?

	Andrew