linux-kernel - Re: [PATCH v2] of: property: fw_devlink: Add support for "phy-handle" property

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Message-ID: <CAL_JsqKXR=Kkx+yKcYv7R3uAeff_HLKSPGr5Y2RBC_=VJmypJQ@mail.gmail.com>
Date:   Mon, 23 Aug 2021 17:08:25 -0500
From:   Rob Herring <robh+dt@...nel.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Frank Rowand <frowand.list@...il.com>,
        netdev <netdev@...r.kernel.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@...ts.infradead.org>
Subject: Re: [PATCH v2] of: property: fw_devlink: Add support for "phy-handle" property

On Mon, Aug 23, 2021 at 3:49 PM Saravana Kannan <saravanak@...gle.com> wrote:
>
> On Mon, Aug 23, 2021 at 12:58 PM Andrew Lunn <andrew@...n.ch> wrote:
> >
> > > PHY seems to be one of those cases where it's okay to have the
> > > compatible property but also okay to not have it.
> >
> > Correct. They are like PCI or USB devices. You can ask it, what are
> > you? There are two registers in standard locations which give you a
> > vendor and product ID. We use that to find the correct driver.
>
> For all the cases of PHYs that currently don't need any compatible
> string, requiring a compatible string of type "ethernet-phy-standard"
> would have been nice. That would have made PHYs consistent with the
> general DT norm of "you need a compatible string to be matched with
> the device". Anyway, it's too late to do that now. So I'll have to
> deal with this some other way (I have a bunch of ideas, so it's not
> the end of the world).

This is not the first time the need for compatible strings for MDIO
devices has come up, but MDIO devices are special (evidently). I
should have taken a harder stance on this which should be simply, if
your device requires having a node in DT, then it requires a
compatible string.

Rob