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Date:   Wed, 18 Apr 2018 13:41:19 +0200
From:   Alban <albeu@free.fr>
To:     Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc:     Alban <albeu@free.fr>, linux-kernel@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Brian Norris <computersforpeace@gmail.com>,
        Boris Brezillon <boris.brezillon@free-electrons.com>,
        Marek Vasut <marek.vasut@gmail.com>,
        Richard Weinberger <richard@nod.at>,
        Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>,
        devicetree@vger.kernel.org, linux-mtd@lists.infradead.org
Subject: Re: [PATCH v3 1/3] nvmem: Update the OF binding to use a subnode
 for the cells list
Message-ID: <20180418134119.2e587621@avionic-0020>
In-Reply-To: <20180417180040.04f53495@avionic-0020>
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On Tue, 17 Apr 2018 18:00:40 +0200
Alban <albeu@free.fr> wrote:

> On Tue, 17 Apr 2018 16:44:01 +0100
> Srinivas Kandagatla <srinivas.kandagatla@linaro.org> wrote:
>=20
> > Thanks for explaining,
> >=20
> > On 17/04/18 15:54, Alban wrote: =20
> > > This will not only allow reading the calibration data from nvmem, but
> > > will also create a partition on the MTD device, which is not acceptab=
le.
> > > With my proposed binding this would become:
> > >=20
> > > flash@0 {
> > > 	#address-cells =3D <1>;
> > > 	#size-cells =3D <1>;
> > > 	compatible =3D "s25sl064a";
> > > 	reg =3D <0>;
> > >=20
> > > 	nvmem-cells {
> > > 		compatible =3D "nvmem-cells";
> > > 		#address-cells =3D <1>;
> > > 		#address-cells =3D <1>;
> > >=20
> > > 		calibration: calib@404 {
> > > 			reg =3D <0x404 0x10>;
> > > 		};
> > > 	};   =20
> >=20
> > Why can't we make nvmem-cells node a nvmem provider in this case?
> > Which should work! =20
>=20
> TBH I just copied what have been done to fix the same problem with the
> MTD partitions. But yes we could also just extend the current binding
> to require a compatible string on each nvmem-cell, which would not
> require any code change to support.

However this scheme will not work if the device node binding already
have subnodes with addresses. The addressing, as specified by
#address-cells and #size-cells, might be incompatible or might overlap.
Using the nvmem-cells subnode solve this problem.

Alban


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