netdev - Re: [PATCH net-next] net: dsa: Deal with non-existing PHY/fixed-link

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Date:   Mon, 10 Jun 2019 22:53:31 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] net: dsa: Deal with non-existing PHY/fixed-link

On Mon, 10 Jun 2019 at 22:31, Florian Fainelli <f.fainelli@...il.com> wrote:
>
> We need to specifically deal with phylink_of_phy_connect() returning
> -ENODEV, because this can happen when a CPU/DSA port does connect
> neither to a PHY, nor has a fixed-link property. This is a valid use
> case that is permitted by the binding and indicates to the switch:
> auto-configure port with maximum capabilities.
>
> Fixes: 0e27921816ad ("net: dsa: Use PHYLINK for the CPU/DSA ports")
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  net/dsa/port.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/dsa/port.c b/net/dsa/port.c
> index d74bc9df1359..dde3085ff065 100644
> --- a/net/dsa/port.c
> +++ b/net/dsa/port.c
> @@ -622,7 +622,7 @@ static int dsa_port_phylink_register(struct dsa_port *dp)
>         }
>
>         err = phylink_of_phy_connect(dp->pl, port_dn, 0);
> -       if (err) {
> +       if (err && err != -ENODEV) {
>                 pr_err("could not attach to PHY: %d\n", err);
>                 goto err_phy_connect;
>         }
> --
> 2.17.1
>

Hi Florian,

Can you give an example of when this is a valid use case, and why
fixed-link is not appropriate?

Regards,
-Vladimir