Re: [PATCH net-next v3 02/11] net: phy: introduce phy_has_c45_registers()

[Michael Walle]

Hi Andrew,

Am 2023-07-19 09:11, schrieb Michael Walle:
> > > diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
> > > index a64186dc53f8..686a57d56885 100644
> > > --- a/drivers/net/phy/phy-core.c
> > > +++ b/drivers/net/phy/phy-core.c
> > > @@ -556,7 +556,7 @@ int __phy_read_mmd(struct phy_device *phydev, int 
> > > devad, u32 regnum)
> > >
> > >  	if (phydev->drv && phydev->drv->read_mmd) {
> > >  		val = phydev->drv->read_mmd(phydev, devad, regnum);
> > > -	} else if (phydev->is_c45) {
> > > +	} else if (phy_has_c45_registers(phydev)) {
> >
> > This i would say should be
> >
> > phy_has_c45_transfers(phydev). This is about, can we do C45 transfers
> > on the bus, and if not, fall back to C45 over C22.
>
> Shouldn't this then be a bus property? I.e. 
> mdiobus_has_c45_transfers().
> I've have a similar helper introduced in 9/11:
>
> static inline bool mdiobus_supports_c45(struct mii_bus *bus)
> {
>     return bus->read_c45 && !bus->prevent_c45_access;
> }
>
> > >  static int phylink_sfp_connect_phy(void *upstream, struct phy_device 
> > > *phy)
> > > diff --git a/include/linux/phy.h b/include/linux/phy.h
> > > index 11c1e91563d4..fdb3774e99fc 100644
> > > --- a/include/linux/phy.h
> > > +++ b/include/linux/phy.h
> > > @@ -766,6 +766,11 @@ static inline struct phy_device 
> > > *to_phy_device(const struct device *dev)
> > >  	return container_of(to_mdio_device(dev), struct phy_device, mdio);
> > >  }
> > >
> > > +static inline bool phy_has_c45_registers(struct phy_device *phydev)
> > > +{
> > > +	return phydev->is_c45;
> > > +}
> >
> > And this is where it gets interesting. I think as a first step, you
> > should implement the four functions:
> >
> > phy_has_c22_registers()
> > phy_has_c45_registers()
> > phy_has_c22_transfers()
> > phy_has_c45_transfers()
> >
> > based on this. So there is initially no functional change.
> >
> >
> > You can then change the implementation of _transfers() based on what
> > the MDIO bus can do, plus the quirk for if a FUBAR microchip PHY has
> > been found.
>
> See above. Shouldn't it be mdiobus_...() then?
>
> > Then change the implementation of _registers() based on the results of
> > probing for the ID registers.
>
> So this is where I cannot follow. Right now there is
> (1) probing via bus scan
> (2) probing via DT (or maybe also ACPI)
>
> With (1) you we have scan_c22(), so if successful, 
> phy_has_c22_registers()
> will return true, right? But it's not that clear for
> phy_has_c45_registers(), because sometimes we prevent that scan. So
> the PHY might have c45 but we don't know.
>
> For (2) we don't even do a c22 scan if we know if its a C45 PHY (or the
> other way around). I'm not sure we can reliably tell (at the end of 
> this
> series) if a phy has c22 register, c45 registers or both.

Any news here?

-michael