Re: [PATCH v2 05/11] dt-bindings: net: sun4i-emac: Convert the binding to a schemas

From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Rob Herring <robh+dt@kernel.org>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Alexandre Torgue" <alexandre.torgue@st.com>,
	devicetree@vger.kernel.org,
	"Antoine Ténart" <antoine.tenart@bootlin.com>,
	netdev <netdev@vger.kernel.org>,
	linux-stm32@st-md-mailman.stormreply.com,
	"Chen-Yu Tsai" <wens@csie.org>,
	"Maxime Coquelin" <mcoquelin.stm32@gmail.com>,
	"Maxime Chevallier" <maxime.chevallier@bootlin.com>,
	"Frank Rowand" <frowand.list@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
	<linux-arm-kernel@lists.infradead.org>,
	"Heiner Kallweit" <hkallweit1@gmail.com>
Subject: Re: [PATCH v2 05/11] dt-bindings: net: sun4i-emac: Convert the binding to a schemas
Date: Tue, 11 Jun 2019 16:58:56 +0200	[thread overview]
Message-ID: <20190611145856.ua2ggkn6ccww6vpp@flea> (raw)
In-Reply-To: <CAL_JsqJahCJcdu=+fA=ewbGezuEJ2W6uwMVxkQpdY6w+1OWVVA@mail.gmail.com>

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Hi Rob,

On Mon, Jun 10, 2019 at 12:59:29PM -0600, Rob Herring wrote:
> On Mon, Jun 10, 2019 at 8:31 AM Andrew Lunn <andrew@lunn.ch> wrote:
> >
> > > +required:
> > > +  - compatible
> > > +  - reg
> > > +  - interrupts
> > > +  - clocks
> > > +  - phy
> > > +  - allwinner,sram
> >
> > Quoting ethernet.txt:
> >
> > - phy: the same as "phy-handle" property, not recommended for new bindings.
> >
> > - phy-handle: phandle, specifies a reference to a node representing a PHY
> >   device; this property is described in the Devicetree Specification and so
> >   preferred;
> >
> > Can this be expressed in Yaml? Accept phy, but give a warning. Accept
> > phy-handle without a warning? Enforce that one or the other is
> > present?
>
> The common schema could have 'phy: false'. This works as long as we've
> updated (or plan to) all the dts files to use phy-handle. The issue is
> how far back do you need kernels to work with newer dtbs.

I guess another question being raised by this is how hard do we want
to be a deprecating things, and should the DT validation be a tool to
enforce that validation.

For example, you've used in you GPIO meta-schema false for anything
ending with -gpio, since it's deprecated. This means that we can't
convert any binding using a deprecated property without introducing a
build error in the schemas, which in turn means that you'll have a lot
of friction to support schemas, since you would have to convert your
driver to support the new way of doing things, before being able to
have a schema for your binding.

And then, we need to agree on how to express the deprecation. I guess
we could allow the deprecated keyword that will be there in the
draft-8, instead of ad-hoc solutions?

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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