netdev - Re: [net-next: PATCH v2 2/7] net: mdiobus: Introduce fwnode_mdbiobus

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Message-ID: <CAPv3WKdOkxV695DbhhYr+wf1rnphtj-pyERZ-74RrdZyQJGt=g@mail.gmail.com>
Date:   Thu, 17 Jun 2021 01:50:55 +0200
From:   Marcin Wojtas <mw@...ihalf.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Grzegorz Jaszczyk <jaz@...ihalf.com>,
        Grzegorz Bernacki <gjb@...ihalf.com>, upstream@...ihalf.com,
        Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@....com>,
        Jon Nettleton <jon@...id-run.com>,
        Tomasz Nowicki <tn@...ihalf.com>, rjw@...ysocki.net,
        lenb@...nel.org
Subject: Re: [net-next: PATCH v2 2/7] net: mdiobus: Introduce fwnode_mdbiobus_register()

śr., 16 cze 2021 o 21:33 Andrew Lunn <andrew@...n.ch> napisał(a):
>
> On Wed, Jun 16, 2021 at 09:07:54PM +0200, Marcin Wojtas wrote:
> > This patch introduces a new helper function that
> > wraps acpi_/of_ mdiobus_register() and allows its
> > usage via common fwnode_ interface.
> >
> > Fall back to raw mdiobus_register() in case CONFIG_FWNODE_MDIO
> > is not enabled, in order to satisfy compatibility
> > in all future user drivers.
>
> > Signed-off-by: Marcin Wojtas <mw@...ihalf.com>
> > ---
> >  include/linux/fwnode_mdio.h    | 12 +++++++++++
> >  drivers/net/mdio/fwnode_mdio.c | 22 ++++++++++++++++++++
> >  2 files changed, 34 insertions(+)
> >
> > diff --git a/include/linux/fwnode_mdio.h b/include/linux/fwnode_mdio.h
> > index faf603c48c86..13d4ae8fee0a 100644
> > --- a/include/linux/fwnode_mdio.h
> > +++ b/include/linux/fwnode_mdio.h
> > @@ -16,6 +16,7 @@ int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
> >  int fwnode_mdiobus_register_phy(struct mii_bus *bus,
> >                               struct fwnode_handle *child, u32 addr);
> >
> > +int fwnode_mdiobus_register(struct mii_bus *bus, struct fwnode_handle *fwnode);
> >  #else /* CONFIG_FWNODE_MDIO */
> >  int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
> >                                      struct phy_device *phy,
> > @@ -30,6 +31,17 @@ static inline int fwnode_mdiobus_register_phy(struct mii_bus *bus,
> >  {
> >       return -EINVAL;
> >  }
> > +
> > +static inline int fwnode_mdiobus_register(struct mii_bus *bus,
> > +                                       struct fwnode_handle *fwnode)
> > +{
> > +     /*
> > +      * Fall back to mdiobus_register() function to register a bus.
> > +      * This way, we don't have to keep compat bits around in drivers.
> > +      */
> > +
> > +     return mdiobus_register(mdio);
> > +}
>
> I'm not sure this fallback is correct.
>
> Any driver which decides to use fwmode is going to select it. If it is
> not selected, you want a link time error, or a compiler time error to
> tell you, you are missing FWNODE_MDIO. Calling mdiobus_register() is
> unlikely to work, or the driver would of done that directly.
>

This kind of fallback is done in of_mdiobus_register and acpi_mdiobus_register.

Actually mvmdio driver is using this fallback for non-dt platforms
(e.g. Orion). Therefore I would prefer to keep the current behavior.

Best regards,
Marcin