netdev - RE: [PATCH net-next v5] Add Mellanox BlueField Gigabit Ethernet driver

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Message-ID: <CH2PR12MB3895FA4354E69D830F39CDC8D73E9@CH2PR12MB3895.namprd12.prod.outlook.com>
Date:   Tue, 1 Jun 2021 12:48:25 +0000
From:   Asmaa Mnebhi <asmaa@...dia.com>
To:     Andrew Lunn <andrew@...n.ch>,
        David Thompson <davthompson@...dia.com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Liming Sun <limings@...dia.com>
Subject: RE: [PATCH net-next v5] Add Mellanox BlueField Gigabit Ethernet
 driver

Hi Andrew,

Thank you for your feedback.

Our Hardware only supports a single configuration: symmetric flow control, nothing else. This is why we have to enforce this, and there is not adjustment to do.
The only reason we set priv->rx_pause and priv->tx_pause here is for ethtool purposes.

Thanks.
Asmaa
-----Original Message-----
From: Andrew Lunn <andrew@...n.ch> 
Sent: Friday, May 28, 2021 8:22 PM
To: David Thompson <davthompson@...dia.com>
Cc: davem@...emloft.net; kuba@...nel.org; netdev@...r.kernel.org; Liming Sun <limings@...dia.com>; Asmaa Mnebhi <asmaa@...dia.com>
Subject: Re: [PATCH net-next v5] Add Mellanox BlueField Gigabit Ethernet driver

> +static void mlxbf_gige_adjust_link (struct net_device *netdev) {
> +	struct mlxbf_gige *priv = netdev_priv(netdev);
> +	struct phy_device *phydev = netdev->phydev;
> +
> +	if (phydev->link) {
> +		priv->rx_pause = phydev->pause;
> +		priv->tx_pause = phydev->pause;
> +	}

...

> +	/* MAC supports symmetric flow control */
> +	phy_support_sym_pause(phydev);

What i don't see anywhere is you acting on the results of the pause negotiation. It could be, mlxbf_gige_adjust_link() tells you the peer does not support pause, and you need to disable it in this MAC as well. It is a negotiation, after all.

	Andrew