linux-kernel - Re: [PATCH net v2] net: stmmac: Handle disabled MDIO busses from devicetree

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Message-ID: <f2pf2g23ln4qcoqxidy55plysn735qtfspj6nuu6f7isqxotp2@rj6ejru5eon7>
Date:   Wed, 13 Dec 2023 16:09:12 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Andrew Halaney <ahalaney@...hat.com>
Cc:     Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Andrew Lunn <andrew@...n.ch>, netdev@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Simon Horman <horms@...nel.org>
Subject: Re: [PATCH net v2] net: stmmac: Handle disabled MDIO busses from
 devicetree

On Tue, Dec 12, 2023 at 04:18:33PM -0600, Andrew Halaney wrote:
> Many hardware configurations have the MDIO bus disabled, and are instead
> using some other MDIO bus to talk to the MAC's phy.
> 
> of_mdiobus_register() returns -ENODEV in this case. Let's handle it
> gracefully instead of failing to probe the MAC.
> 
> Fixes: 47dd7a540b8a ("net: add support for STMicroelectronics Ethernet controllers.")
> Signed-off-by: Andrew Halaney <ahalaney@...hat.com>
> ---
> Changes in v2:
> - Improve error handling code (Serge)
> - Fix malformed Fixes tag (Simon)
> - Link to v1: https://lore.kernel.org/r/20231211-b4-stmmac-handle-mdio-enodev-v1-1-73c20c44f8d6@redhat.com

Looking good. Thanks!
Reviewed-by: Serge Semin <fancer.lancer@...il.com>

-Serge(y)

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> index fa9e7e7040b9..0542cfd1817e 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> @@ -591,7 +591,11 @@ int stmmac_mdio_register(struct net_device *ndev)
>  	new_bus->parent = priv->device;
>  
>  	err = of_mdiobus_register(new_bus, mdio_node);
> -	if (err != 0) {
> +	if (err == -ENODEV) {
> +		err = 0;
> +		dev_info(dev, "MDIO bus is disabled\n");
> +		goto bus_register_fail;
> +	} else if (err) {
>  		dev_err_probe(dev, err, "Cannot register the MDIO bus\n");
>  		goto bus_register_fail;
>  	}
> 
> ---
> base-commit: bbd220ce4e29ed55ab079007cff0b550895258eb
> change-id: 20231211-b4-stmmac-handle-mdio-enodev-82168de68c6a
> 
> Best regards,
> -- 
> Andrew Halaney <ahalaney@...hat.com>
>