linux-kernel - Re: [PATCH net-next 6/6] net: dsa: lantiq_gswip: move MDIO bus registration to .setup()

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Message-ID: <3b0399d3535ba2546274733c3adb5266adc31094.camel@siemens.com>
Date: Tue, 26 Aug 2025 07:30:04 +0000
From: "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
To: "hauke@...ke-m.de" <hauke@...ke-m.de>, "olteanv@...il.com"
	<olteanv@...il.com>, "davem@...emloft.net" <davem@...emloft.net>,
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CC: "john@...ozen.org" <john@...ozen.org>, "Stockmann, Lukas"
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Subject: Re: [PATCH net-next 6/6] net: dsa: lantiq_gswip: move MDIO bus
 registration to .setup()

Hi!

On Tue, 2025-08-26 at 01:14 +0100, Daniel Golle wrote:
> Instead of registering the switch MDIO bus in the probe() function, move
> the call to gswip_mdio() into the .setup() DSA switch op, so it can be
> reused independently of the probe() function.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
>  drivers/net/dsa/lantiq_gswip.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/dsa/lantiq_gswip.c b/drivers/net/dsa/lantiq_gswip.c
> index 23b68047f3c4..9ec262ec3a11 100644
> --- a/drivers/net/dsa/lantiq_gswip.c
> +++ b/drivers/net/dsa/lantiq_gswip.c
> @@ -627,6 +627,13 @@ static int gswip_setup(struct dsa_switch *ds)
>  	/* Configure the MDIO Clock 2.5 MHz */
>  	gswip_mdio_mask(priv, 0xff, 0x09, GSWIP_MDIO_MDC_CFG1);
>  
> +	/* bring up the mdio bus */
> +	err = gswip_mdio(priv);
> +	if (err) {
> +		dev_err(priv->dev, "mdio bus setup failed\n");
> +		return err;
> +	}
> +
>  	/* Disable the xMII interface and clear it's isolation bit */
>  	for (i = 0; i < priv->hw_info->max_ports; i++)
>  		gswip_mii_mask_cfg(priv,
> @@ -1973,13 +1980,6 @@ static int gswip_probe(struct platform_device *pdev)
>  					     "gphy fw probe failed\n");
>  	}
>  
> -	/* bring up the mdio bus */
> -	err = gswip_mdio(priv);
> -	if (err) {
> -		dev_err_probe(dev, err, "mdio probe failed\n");
> -		goto gphy_fw_remove;
> -	}
> -
>  	err = dsa_register_switch(priv->ds);
>  	if (err) {
>  		dev_err_probe(dev, err, "dsa switch registration failed\n");

Moving to .setup callback makes sense to me in general, but isn't a
.teardown callback necessary as well to de-register the bus?

Maybe the resource-managed devm_mdiobus_alloc() and devm_of_mdiobus_register()
have to be downgraded to their corresponding non-managed variants?

-- 
Alexander Sverdlin
Siemens AG
www.siemens.com