linux-kernel - Re: [PATCH 1/5] net: mdio: Mask PHY only when its ACPI node is present

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Date:   Thu, 21 Apr 2022 20:18:40 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     hkallweit1@...il.com, linux@...linux.org.uk,
        peppe.cavallaro@...com, alexandre.torgue@...s.st.com,
        joabreu@...opsys.com, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] net: mdio: Mask PHY only when its ACPI node is present

On Thu, Apr 21, 2022 at 7:40 PM Andrew Lunn <andrew@...n.ch> wrote:
>
> On Thu, Apr 21, 2022 at 10:58:40AM +0800, Kai-Heng Feng wrote:
> > On Wed, Apr 20, 2022 at 10:47 PM Andrew Lunn <andrew@...n.ch> wrote:
> > >
> > > On Wed, Apr 20, 2022 at 08:40:48PM +0800, Kai-Heng Feng wrote:
> > > > Not all PHY has an ACPI node, for those nodes auto probing is still
> > > > needed.
> > >
> > > Why do you need this?
> > >
> > > Documentation/firmware-guide/acpi/dsd/phy.rst
> > >
> > > There is nothing here about there being PHYs which are not listed in
> > > ACPI. If you have decided to go the ACPI route, you need to list the
> > > PHYs.
> >
> > This is for backward-compatibility. MAC can have ACPI node but PHY may
> > not have one.
>
> And if the PHY does not have an ACPI node, fall back to
> mdiobus_register(). This is what of_mdiobus_register() does. If
> np=NULL, it calls mdiobus_register() and skips all the OF stuff.

The equivalent to this scenario is that when MAC doesn't have ACPI node.
But yes it can unmask the PHYs if no ACPI node is found, then call
mdiobus_register().

Kai-Heng

>
>          Andrew