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From: "Michael Walle" <michael@walle.cc>
To: "Linus Walleij" <linusw@kernel.org>,
	"Manikandan Muralidharan" <manikandan.m@microchip.com>
Cc: <pratyush@kernel.org>, <mwalle@kernel.org>,
	<takahiro.kuwano@infineon.com>, <miquel.raynal@bootlin.com>,
	<richard@nod.at>, <vigneshr@ti.com>, <robh@kernel.org>,
	<krzk+dt@kernel.org>, <conor+dt@kernel.org>, <srini@kernel.org>,
	<nicolas.ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
	<claudiu.beznea@tuxon.dev>, <linux@armlinux.org.uk>,
	<richardcochran@gmail.com>, <arnd@arndb.de>,
	<linux-mtd@lists.infradead.org>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>, <netdev@vger.kernel.org>
Subject: Re: [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM
Date: Wed, 01 Jul 2026 10:34:35 +0200	[thread overview]
Message-ID: <DJN3HIIAY4LE.3MXU9Q2YFSCJJ@walle.cc> (raw)
In-Reply-To: <CAD++jL=FkEfpz-LW0vmPpZ28fLfGFMWo5E479Mapz55YUxKNAQ@mail.gmail.com>

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Hi,

>> Add an optional "sfdp" child node (compatible "jedec,sfdp") that
>> describes the SFDP as a read-only NVMEM provider via nvmem.yaml, so its
>> contents (e.g. a vendor EUI-48/EUI-64) can be read through NVMEM cells.
>>
>> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
>
> I would expect it to follow nvmem conventions like this, notice
> compatibles specific-to-general with sfdp first:


> sfdp {
>     /* NVMEM provided by SFDP */
>     compatible = "jedec,sfdp", "nvmem-cells";
>     label = "SFDP";

Isn't using label frowned upon? I wouldn't add that to the example.

>     read-only;
>     #address-cells = <1>;
>     #size-cells = <1>;
>
>     mac0: macaddr@0x00 {
>         reg = <0x00 0x06>;
>     };
>     mac1: macaddr@0x06 {
>         reg = <0x06 0x06>;
>     };
> };

If I'm correct, this is the old style, see commit bd912c991d2e
("dt-bindings: nvmem: layouts: add fixed-layout"). So it should
eventually look like:

sfdp {
     compatible = "jedec,sfdp";

     nvmem-layout {
	     compatible = "microchip,sst26vf-sfdp-eui";
     };
};

Which is what patch series will lead to.

Also I'm not sure if we really need to add the "nvmem-cells" here.
IIRC in MTD it was there to tell a driver to add an nvmem device to
an already existing compatible/node.

Apart from the MTD case, I've just found qcom,smem-part,yaml which
has compatible = "nvmem-cells".

-michael

> Your example should definitely be more elaborate like this,
> just an opaque sfdp node will not suffice. Maybe a separate
> example?
>
> Yours,
> Linus Walleij


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  reply	other threads:[~2026-07-01  8:35 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-30  9:23 [PATCH v4 0/7] Read MAC address from SST vendor specific SFDP region Manikandan Muralidharan
2026-06-30  9:24 ` [PATCH v4 1/7] dt-bindings: mtd: jedec,spi-nor: allow the SFDP to be exposed via NVMEM Manikandan Muralidharan
2026-06-30 22:12   ` Linus Walleij
2026-07-01  8:34     ` Michael Walle [this message]
2026-07-01 10:53       ` Linus Walleij
2026-06-30  9:24 ` [PATCH v4 2/7] dt-bindings: nvmem: layouts: add Microchip/SST SFDP EUI layout Manikandan Muralidharan
2026-06-30  9:24 ` [PATCH v4 3/7] mtd: spi-nor: sfdp: expose the SFDP as a read-only NVMEM device Manikandan Muralidharan
2026-06-30 22:25   ` Linus Walleij
2026-06-30  9:24 ` [PATCH v4 4/7] nvmem: layouts: add Microchip/SST SFDP EUI layout driver Manikandan Muralidharan
2026-06-30  9:24 ` [PATCH v4 5/7] ARM: dts: microchip: sama5d27_wlsom1: use fixed-partitions for QSPI flash Manikandan Muralidharan
2026-06-30 22:27   ` Linus Walleij
2026-06-30  9:24 ` [PATCH v4 6/7] ARM: dts: microchip: sama5d27_wlsom1: read MAC address from QSPI SFDP Manikandan Muralidharan
2026-06-30  9:24 ` [PATCH v4 7/7] ARM: configs: sama5: enable Microchip/SST SFDP EUI NVMEM layout Manikandan Muralidharan

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