netdev - Re: [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver

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Message-ID: <20201130132835.7ln72bbdr36spuwm@mchp-dev-shegelun>
Date:   Mon, 30 Nov 2020 14:28:35 +0100
From:   Steen Hegelund <steen.hegelund@...rochip.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Lars Povlsen <lars.povlsen@...rochip.com>,
        Bjarni Jonasson <bjarni.jonasson@...rochip.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Microsemi List <microsemi@...ts.bootlin.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver

On 28.11.2020 20:03, Andrew Lunn wrote:
>EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
>> +static int sparx5_port_open(struct net_device *ndev)
>> +{
>> +     struct sparx5_port *port = netdev_priv(ndev);
>> +     int err = 0;
>> +
>> +     sparx5_port_enable(port, true);
>> +     if (port->conf.phy_mode != PHY_INTERFACE_MODE_NA) {
>> +             err = phylink_of_phy_connect(port->phylink, port->of_node, 0);
>> +             if (err) {
>> +                     netdev_err(ndev, "Could not attach to PHY\n");
>> +                     return err;
>> +             }
>> +     }
>
>This looks a bit odd. PHY_INTERFACE_MODE_NA means don't touch,
>something else has already configured the MAC-PHY mode in the PHY.
>You should not not connect the PHY because of this.

Hmm.  I will have to revisit this again.  The intent was to be able to
destinguish between regular PHYs and SFPs (as read from the DT).
But maybe the phylink_of_phy_connect function handles this
automatically...
>
>> +void sparx5_destroy_netdev(struct sparx5 *sparx5, struct sparx5_port *port)
>> +{
>> +     if (port->phylink) {
>> +             /* Disconnect the phy */
>> +             if (rtnl_trylock()) {
>
>Why do you use rtnl_trylock()?

The sparx5_port_stop() in turn calls phylink_stop() that expects the lock
to be taken.  Should I rather just call rtnl_lock()?

Thanks for your comments

/Steen


>
>    Andrew

BR
Steen

---------------------------------------
Steen Hegelund
steen.hegelund@...rochip.com