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Date:   Fri, 20 May 2022 17:22:44 +0200
From:   =?UTF-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= <clement.leger@bootlin.com>
To:     Vladimir Oltean <olteanv@gmail.com>
Cc:     "Russell King (Oracle)" <linux@armlinux.org.uk>,
        Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Magnus Damm <magnus.damm@gmail.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Herve Codina <herve.codina@bootlin.com>,
        =?UTF-8?B?TWlxdcOobA==?= Raynal <miquel.raynal@bootlin.com>,
        Milan Stevanovic <milan.stevanovic@se.com>,
        Jimmy Lalande <jimmy.lalande@se.com>,
        Pascal Eberhard <pascal.eberhard@se.com>,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-renesas-soc@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH net-next v5 05/13] net: pcs: add Renesas MII converter
 driver
Message-ID: <20220520172244.1f17f736@fixe.home>
In-Reply-To: <20220520084914.5x6bfu4qaza4tqcz@skbuf>
References: <20220519153107.696864-1-clement.leger@bootlin.com>
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        <YoZvZj9sQL2GZAI3@shell.armlinux.org.uk>
        <20220520095241.6bbccdf0@fixe.home>
        <20220520084914.5x6bfu4qaza4tqcz@skbuf>
Organization: Bootlin
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Le Fri, 20 May 2022 11:49:14 +0300,
Vladimir Oltean <olteanv@gmail.com> a =C3=A9crit :

> On Fri, May 20, 2022 at 09:52:41AM +0200, Cl=C3=A9ment L=C3=A9ger wrote:
> > > Also, as a request to unbind this driver would be disasterous to user=
s,
> > > I think you should set ".suppress_bind_attrs =3D true" to prevent the
> > > sysfs bind/unbind facility being available. This doesn't completely
> > > solve the problem. =20
> >=20
> > Acked. What should I do to make it more robust ? Should I use a
> > refcount per pdev and check that in the remove() callback to avoid
> > removing the pdev if used ? =20
>=20
> I wonder, if you call device_link_add(ds->dev, miic->dev, DL_FLAG_AUTOREM=
OVE_CONSUMER),
> wouldn't that be enough to auto-unbind the DSA driver when the MII
> converter driver unbinds?

I looiked at that a bit and I'm not sure how to achieve that cleanly. If
I need to create this link, then I need to do it once for the dsa switch
device. However, currently, the way I get the references to the MII
converter are via the pcs-handle properties which are for each port.

So, I'm not sure creating the link multiple times in miic_create() would
be ok and also, I'm not sure how to create the link once without adding
a specific property which points on the MII converter node and use that
to create the link by adding miic_device_add_link() for instance.

Do you have any preference ?

Thanks,

--=20
Cl=C3=A9ment L=C3=A9ger,
Embedded Linux and Kernel engineer at Bootlin
https://bootlin.com