linux-kernel - Re: [PATCH net-next v4 8/9] net: dsa: dsa_slave_phy_connect(): extend phy's flags with port specific phy flags

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Date:   Mon, 14 Jun 2021 05:37:30 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Vladimir Oltean <olteanv@...il.com>,
        Woojung Huh <woojung.huh@...rochip.com>,
        Andrew Lunn <andrew@...n.ch>,
        Michael Grzeschik <m.grzeschik@...gutronix.de>,
        Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Vivien Didelot <vivien.didelot@...il.com>,
        kernel@...gutronix.de, Jakub Kicinski <kuba@...nel.org>,
        UNGLinuxDriver@...rochip.com,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH net-next v4 8/9] net: dsa: dsa_slave_phy_connect():
 extend phy's flags with port specific phy flags

On Fri, Jun 11, 2021 at 04:26:33PM -0700, Florian Fainelli wrote:
> 
> 
> On 6/11/2021 12:24 PM, Vladimir Oltean wrote:
> > On Fri, Jun 11, 2021 at 09:15:26AM +0200, Oleksij Rempel wrote:
> >> This patch extends the flags of the phy that's being connected with the
> >> port specific flags of the switch port.
> >>
> >> This is needed to handle a port specific erratum of the KSZ8873 switch,
> >> which is added in a later patch.
> >>
> >> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> >> ---
> > 
> > What happens differently between having this patch and not having it?
> 
> The current get_phy_flags() is only processed when we connect to a PHY
> via a designed phy-handle property via phylink_of_phy_connect((, but if
> we fallback on the internal MDIO bus created by a switch and take the
> dsa_slave_phy_connect() path then we would not be processing that flag
> and using it at PHY connection time. Oleksij, your proposed patch fails
> to check that dsa_switch_ops::get_phy_flags is actually non-NULL, how
> about this approach instead where we only fetch the flags once, and we
> deal with an option get_phy_flags callback too:

ok, sounds good.
Thank you.

> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
> index d4756b920108..ba7866ec946f 100644
> --- a/net/dsa/slave.c
> +++ b/net/dsa/slave.c
> @@ -1749,7 +1749,7 @@ static void dsa_slave_phylink_fixed_state(struct
> phylink_config *config,
>  }
> 
>  /* slave device setup
> *******************************************************/
> -static int dsa_slave_phy_connect(struct net_device *slave_dev, int addr)
> +static int dsa_slave_phy_connect(struct net_device *slave_dev, int
> addr, u32 flags)
>  {
>         struct dsa_port *dp = dsa_slave_to_port(slave_dev);
>         struct dsa_switch *ds = dp->ds;
> @@ -1760,6 +1760,8 @@ static int dsa_slave_phy_connect(struct net_device
> *slave_dev, int addr)
>                 return -ENODEV;
>         }
> 
> +       slave_dev->phydev->dev_flags |= flags;
> +
>         return phylink_connect_phy(dp->pl, slave_dev->phydev);
>  }
> 
> @@ -1804,7 +1806,7 @@ static int dsa_slave_phy_setup(struct net_device
> *slave_dev)
>                 /* We could not connect to a designated PHY or SFP, so
> try to
>                  * use the switch internal MDIO bus instead
>                  */
> -               ret = dsa_slave_phy_connect(slave_dev, dp->index);
> +               ret = dsa_slave_phy_connect(slave_dev, dp->index,
> phy_flags);
>                 if (ret) {
>                         netdev_err(slave_dev,
>                                    "failed to connect to port %d: %d\n",
> -- 
> Florian
> 
> 

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