Re: [PATCH net-next v4 4/5] net: mdio: realtek-rtl9300: reject duplicate MDIO bus IDs

[netdev-bot+sashiko@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue(s) to consider:

Critical: 0 · High: 0 · Medium: 0 · Low: 1

- [Low] Claimed DT-binding-vs-driver mismatch: the series patch "dt-
  bindings: net: realtek,rtl9301-mdio: add clock-frequency" documents a…

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net: mdio: realtek-rtl9300: reject duplicate MDIO bus IDs

The patch makes otto_emdio_probe_one() reject a second mdio-bus child node
that reuses an already registered reg value, instead of relying on the later
failure inside MDIO bus registration. The previously unused priv->bus[] array
is now filled in after a successful registration and used as the duplicate
check.

> diff --git a/drivers/net/mdio/mdio-realtek-rtl9300.c b/drivers/net/mdio/mdio-realtek-rtl9300.c
> index 8ca917d9aea3c..45cbefc52100a 100644
> --- a/drivers/net/mdio/mdio-realtek-rtl9300.c
> +++ b/drivers/net/mdio/mdio-realtek-rtl9300.c

[ ... ]

> @@ -868,6 +871,8 @@ static int otto_emdio_probe_one(struct device *dev, struct otto_emdio_priv *priv
>  	if (err)
>  		return dev_err_probe(dev, err, "cannot register MDIO bus\n");
>  
> +	priv->bus[mdio_bus] = bus;
> +
>  	return 0;
>  }

[Severity: Low]
This is only an ordering observation about the series, not a bug in this
patch.

At this point in the series, the earlier binding patch "dt-bindings: net:
realtek,rtl9301-mdio: add clock-frequency" already documents a per-bus
clock-frequency property (2.5/10 MHz for RTL838x, 1.25/2.5/5 MHz for
RTL839x/930x/931x, plus the RTL839x shared-selector rule), while
otto_emdio_probe_one() still reads only the reg property, so a device tree
setting clock-frequency would be silently ignored on these commits.

The gap closes at the end of the series in "net: mdio: realtek-rtl9300:
support non-default clock frequencies", which adds the consumer in
otto_emdio_probe_one():

	if (of_property_read_u32(node, "clock-frequency", &freq))
		freq = 2500000;
	err = priv->info->set_bus_frequency(bus, freq);

and otto_emdio_8390_set_bus_frequency() relies on exactly the priv->bus[]
bookkeeping added here to program the shared RTL839x selector only once:

	if (priv->bus[0] || priv->bus[1])
		return 0;

Would it be worth mentioning that dependency, or moving the binding patch
next to the driver patch that consumes the property, so that no intermediate
commit documents a property the driver ignores?

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Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260912130451.3757276-1-markus.stockhausen%40gmx.de