Re: [PATCH net-next v11 00/12] net: pcs: Introduce support for fwnode PCS

[Christian Marangi <ansuelsmth@gmail.com>]

On Sun, Aug 09, 2026 at 10:43:27PM +0200, Andrew Lunn wrote:
> > I think the most annoying one will be stmmac with the 3 different PCS
> > implementation but we already handled that in a upcoming ipq50xx driver
> > currently present in OpenWrt mainline.
> 
> stmmac is always annoying :-(
> 
> If this can make it more uniform, make internal and external PCS look
> the same, that would be great.
> 
>

I posted v12 that should smooth stuff even more. I think I found a good way
with the notifier approach.
 
> > @@ -6808,7 +6792,10 @@ static void mvpp2_acpi_start(struct mvpp2_port *port)
> >         };
> >         struct phylink_pcs *pcs;
> > 
> > -       pcs = mvpp2_select_pcs(&port->phylink_config, port->phy_interface);
> > +       if (mvpp2_is_xlg(port->phy_interface))
> > +               pcs = &port->pcs_xlg;
> > +       else
> > +               pcs = &port->pcs_gmac;
> 
> I thought the point of new API was that phylink picked the PCS. Why
> this if? Why not register both and let phylink pick?
> 

Yep I'm not sure of this... If they expose different interface mode then
both can be provided at the same time. I think it was done to reduce the
logic difference and patch delta to the minimum.

> > +static int mvpp2_port_fill_pcs(struct phylink_config *config,
> > +                              struct phylink_pcs **available_pcs,
> > +                              unsigned int num_possible_pcs)
> > +{
> > +       struct mvpp2_port *port = mvpp2_phylink_to_port(config);
> > +
> > +       available_pcs[0] = &port->pcs_gmac;
> > +
> > +       if (mvpp2_port_supports_xlg(port)) {
> > +               if (num_possible_pcs < 2)
> > +                       return -EINVAL;
> 
> This seems like defensive programming. If we said there was two, we
> should assume available_pcs has room for two. I would not even pass
> int num_possible_pcs as a parameter.
> 

Yes the if is redundant. The phylink core code ALWAYS allocate based on the
phylink_config value. The num_possible is just as a validation value of
what the space allocated in available_pcs.

If everyone is ok I can change and include this in the series.

-- 
	Ansuel