Re: [PATCH net-next] net: dsa: mt7530: support OF-based registration of switch MDIO bus

[Arınç ÜNAL]

On 7.01.2024 22:52, Simon Horman wrote:
> On Sat, Jan 06, 2024 at 03:21:42PM +0300, Arınç ÜNAL wrote:
> > From: David Bauer <mail@xxxxxxxxxxxxxxx>
> >
> > Currently the MDIO bus of the switches the MT7530 DSA subdriver controls
> > can only be registered as non-OF-based. Bring support for registering the
> > bus OF-based.
> >
> > The subdrivers that control switches [with MDIO bus] probed on OF must
> > follow this logic to support all cases properly:
> >
> > No switch MDIO bus defined: Populate ds->user_mii_bus, register the MDIO
> > bus, set the interrupts for PHYs if "interrupt-controller" is defined at
> > the switch node. This case should only be covered for the switches which
> > their dt-bindings documentation didn't document the MDIO bus from the
> > start. This is to keep supporting the device trees that do not describe the
> > MDIO bus on the device tree but the MDIO bus is being used nonetheless.
> >
> > Switch MDIO bus defined: Don't populate ds->user_mii_bus, register the MDIO
> > bus, set the interrupts for PHYs if ["interrupt-controller" is defined at
> > the switch node and "interrupts" is defined at the PHY nodes under the
> > switch MDIO bus node].
> >
> > Switch MDIO bus defined but explicitly disabled: If the device tree says
> > status = "disabled" for the MDIO bus, we shouldn't need an MDIO bus at all.
> > Instead, just exit as early as possible and do not call any MDIO API.
> >
> > The use of ds->user_mii_bus is inappropriate when the MDIO bus of the
> > switch is described on the device tree [1], which is why we don't populate
> > ds->user_mii_bus in that case.
> >
> > Link: https://lore.kernel.org/netdev/20231213120656.x46fyad6ls7sqyzv@skbuf/ [1]
> > Suggested-by: David Bauer <mail@xxxxxxxxxxxxxxx>
> > Signed-off-by: Arınç ÜNAL <arinc.unal@xxxxxxxxxx>
> > ---
> >   drivers/net/dsa/mt7530.c | 18 ++++++++++++++----
> >   1 file changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> > index 391c4dbdff42..39d7e7ad7154 100644
> > --- a/drivers/net/dsa/mt7530.c
> > +++ b/drivers/net/dsa/mt7530.c
> > @@ -2153,17 +2153,25 @@ mt7530_free_irq(struct mt7530_priv *priv)
> >   static int
> >   mt7530_setup_mdio(struct mt7530_priv *priv)
> >   {
> > +	struct device_node *mnp, *np = priv->dev->of_node;
> >   	struct dsa_switch *ds = priv->ds;
> >   	struct device *dev = priv->dev;
> >   	struct mii_bus *bus;
> >   	static int idx;
> > -	int ret;
> > +	int ret = 0;
> > +
> > +	mnp = of_get_child_by_name(np, "mdio");
> > +
> > +	if (mnp && !of_device_is_available(mnp))
> > +		goto out;
>
> nit: I think it would easier on the eyes to simply
>
> 		return 0;

Will do.

Thanks.
Arınç