linux-kernel - Re: [PATCH net-next] net: stmmac: don't create the MDIO bus if there's no mdio node on DT

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Message-ID: <b3f5c37b-0bc5-f2b7-4132-509b4da7509e@foss.st.com>
Date:   Thu, 10 Aug 2023 17:00:18 +0200
From:   Alexandre TORGUE <alexandre.torgue@...s.st.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        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>,
        Alex Elder <elder@...aro.org>,
        Srini Kandagatla <srinivas.kandagatla@...aro.org>,
        Andrew Halaney <ahalaney@...hat.com>
CC:     <netdev@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH net-next] net: stmmac: don't create the MDIO bus if
 there's no mdio node on DT

On 8/8/23 14:02, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> The stmmac_dt_phy() function that parses the device-tree node of the MAC
> and allocates the MDIO and PHY resources misses one use-case: when the
> MAC doesn't have a fixed link but also doesn't define its own mdio bus
> on the device tree and instead shares the MDIO lines with a different
> MAC with its PHY phandle reaching over into a different node.
> 
> As this function could also use some more readability, rework it to
> handle this use-case and simplify the code.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>   .../ethernet/stmicro/stmmac/stmmac_platform.c | 26 +++++++++----------
>   1 file changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> index be8e79c7aa34..91844673df43 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> @@ -320,12 +320,14 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
>   static int stmmac_dt_phy(struct plat_stmmacenet_data *plat,
>   			 struct device_node *np, struct device *dev)
>   {
> -	bool mdio = !of_phy_is_fixed_link(np);
>   	static const struct of_device_id need_mdio_ids[] = {
>   		{ .compatible = "snps,dwc-qos-ethernet-4.10" },
>   		{},
>   	};
>   
> +	if (of_phy_is_fixed_link(np))
> +		return 0;
> +
>   	if (of_match_node(need_mdio_ids, np)) {
>   		plat->mdio_node = of_get_child_by_name(np, "mdio");
>   	} else {
> @@ -340,20 +342,18 @@ static int stmmac_dt_phy(struct plat_stmmacenet_data *plat,
>   		}
>   	}
>   
> -	if (plat->mdio_node) {
> -		dev_dbg(dev, "Found MDIO subnode\n");
> -		mdio = true;
> -	}
> +	if (!plat->mdio_node)
> +		return 0;
>   
> -	if (mdio) {
> -		plat->mdio_bus_data =
> -			devm_kzalloc(dev, sizeof(struct stmmac_mdio_bus_data),
> -				     GFP_KERNEL);
> -		if (!plat->mdio_bus_data)
> -			return -ENOMEM;
> +	dev_dbg(dev, "Found MDIO subnode\n");
>   
> -		plat->mdio_bus_data->needs_reset = true;
> -	}
> +	plat->mdio_bus_data = devm_kzalloc(dev,
> +					   sizeof(struct stmmac_mdio_bus_data),
> +					   GFP_KERNEL);
> +	if (!plat->mdio_bus_data)
> +		return -ENOMEM;
> +
> +	plat->mdio_bus_data->needs_reset = true;
>   
>   	return 0;
>   }

Acked-by: Alexandre TORGUE <alexandre.torgue@...s.st.com>

Regards
Alex