From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jakub Kicinski <jakub.kicinski@netronome.com>
Subject: Re: [net-next 10/16] net/mlx5: Support PCIe buffer congestion
 handling via Devlink
Date: Wed, 18 Jul 2018 18:49:47 -0700
Message-ID: <20180718184947.6e472ee4@cakuba.netronome.com>
References: <20180719010107.22363-1-saeedm@mellanox.com>
        <20180719010107.22363-11-saeedm@mellanox.com>
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Cc: "David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
        Eran Ben Elisha <eranbe@mellanox.com>
To: Saeed Mahameed <saeedm@mellanox.com>, Jiri Pirko <jiri@resnulli.us>
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On Wed, 18 Jul 2018 18:01:01 -0700, Saeed Mahameed wrote:
> +static const struct devlink_param mlx5_devlink_params[] = {
> +	DEVLINK_PARAM_DRIVER(MLX5_DEVLINK_PARAM_ID_CONGESTION_ACTION,
> +			     "congestion_action",
> +			     DEVLINK_PARAM_TYPE_U8,
> +			     BIT(DEVLINK_PARAM_CMODE_RUNTIME),
> +			     mlx5_devlink_get_congestion_action,
> +			     mlx5_devlink_set_congestion_action, NULL),
> +	DEVLINK_PARAM_DRIVER(MLX5_DEVLINK_PARAM_ID_CONGESTION_MODE,
> +			     "congestion_mode",
> +			     DEVLINK_PARAM_TYPE_U8,
> +			     BIT(DEVLINK_PARAM_CMODE_RUNTIME),
> +			     mlx5_devlink_get_congestion_mode,
> +			     mlx5_devlink_set_congestion_mode, NULL),
> +};

The devlink params haven't been upstream even for a full cycle and
already you guys are starting to use them to configure standard
features like queuing.  

I know your HW is not capable of doing full RED offload, it's a
snowflake.  You tell us you're doing custom DCB configuration hacks on
one side (previous argument we had) and custom devlink parameter
configuration hacks on PCIe.

Perhaps the idea that we're trying to use the existing Linux APIs for
HW configuration only applies to forwarding behaviour.