netdev - Re: [PATCH v3 net-next 13/19] ionic: Add initial ethtool support

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Message-ID: <10c66ecf-6d67-d206-b496-6f8139f218a8@pensando.io>
Date:   Fri, 12 Jul 2019 22:16:31 -0700
From:   Shannon Nelson <snelson@...sando.io>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH v3 net-next 13/19] ionic: Add initial ethtool support

On 7/8/19 7:14 PM, Andrew Lunn wrote:
>> +static int ionic_set_pauseparam(struct net_device *netdev,
>> +				struct ethtool_pauseparam *pause)
>> +{
>> +	struct lif *lif = netdev_priv(netdev);
>> +	struct ionic *ionic = lif->ionic;
>> +	struct ionic_dev *idev = &lif->ionic->idev;
>> +
>> +	u32 requested_pause;
>> +	u32 cur_autoneg;
>> +	int err;
>> +
>> +	cur_autoneg = idev->port_info->config.an_enable ? AUTONEG_ENABLE :
>> +								AUTONEG_DISABLE;
>> +	if (pause->autoneg != cur_autoneg) {
>> +		netdev_info(netdev, "Please use 'ethtool -s ...' to change autoneg\n");
>> +		return -EOPNOTSUPP;
>> +	}
>> +
>> +	/* change both at the same time */
>> +	requested_pause = PORT_PAUSE_TYPE_LINK;
>> +	if (pause->rx_pause)
>> +		requested_pause |= IONIC_PAUSE_F_RX;
>> +	if (pause->tx_pause)
>> +		requested_pause |= IONIC_PAUSE_F_TX;
>> +
>> +	if (requested_pause == idev->port_info->config.pause_type)
>> +		return 0;
>> +
>> +	idev->port_info->config.pause_type = requested_pause;
>> +
>> +	mutex_lock(&ionic->dev_cmd_lock);
>> +	ionic_dev_cmd_port_pause(idev, requested_pause);
>> +	err = ionic_dev_cmd_wait(ionic, devcmd_timeout);
>> +	mutex_unlock(&ionic->dev_cmd_lock);
>> +	if (err)
>> +		return err;
> Hi Shannon
>
> I've no idea what the firmware black box is doing, but this looks
> wrong.
>
> pause->autoneg is about if the results of auto-neg should be used or
> not. If false, just configure the MAC with the pause settings and you
> are done. If the interface is being forced, so autoneg in general is
> disabled, just configure the MAC and you are done.
>
> If pause->autoneg is true and the interface is using auto-neg as a
> whole, you pass the pause values to the PHY for it to advertise and
> trigger an auto-neg. Once autoneg has completed, and the resolved
> settings are available, the MAC is configured with the resolved
> values.
>
> Looking at this code, i don't see any difference between configuring
> the MAC or configuring the PHY. I would expect pause->autoneg to be
> part of requested_pause somehow, so the firmware knows what is should
> do.
>
> 	Andrew

In this device there's actually very little the driver can do to 
directly configure the mac or phy besides passing through to the 
firmware what the user has requested - that happens here for the pause 
values, and in ionic_set_link_ksettings() for autoneg.  The firmware is 
managing the port based on these requests with the help of internally 
configured rules defined in a customer setting.

sln