Hi Rob,

Am 2021-04-20 16:08, schrieb Rob Herring:
On Fri, Apr 16, 2021 at 09:26:03PM +0200, Michael Walle wrote:
Am 2021-04-16 20:44, schrieb Rob Herring:
> On Fri, Apr 16, 2021 at 01:49:23PM +0200, Michael Walle wrote:
> > The goal is to fetch a (base) MAC address from the OTP region of a
> > flash.
> >
> > This is the first part, where I try to add the nvmem provider
> > support to
> > the MTD core.
> >
> > I'm not sure about the device tree bindings. Consider the following
> > two
> > variants:
> >
> > (1)
> >     flash@0 {
> >         ..
> >
> >         otp {
> >             compatible = "mtd-user-otp";
> mtd is a linuxism. Why not just 'nvmem-cells' here or as a fallback if
> we come up with a better name?

There are two different compatibles: "mtd-user-otp" and "mtd-factory-otp" to differentiate what kind of OTP should be used (and both are possible at the same time). Thus nvmem-cells alone won't be enough. We could drop
the "mtd-" prefix though.

Is there a benefit of having the following?
  compatible = "user-otp", "nvmem-cells";

Yes. I assume 'user-otp' tells you something about the region and
'nvmem-cells' tells you that there are child nodes of nvmem data. Of
course 'user-otp' could imply 'nvmem-cells' as you did. I'm fine with
either way.

Ah, if I use both compatibles, then the
schema kicks in, which mandates 'compatible = "nvmem-cells";' and I
get the following errors:

  CHECK   Documentation/devicetree/bindings/mtd/mtd.example.dt.yaml
/home/mwalle/repos/b-linux-arm64/Documentation/devicetree/bindings/mtd/mtd.example.dt.yaml: otp-1: compatible:0: 'nvmem-cells' was expected From schema: /home/mwalle/repos/linux-mw/Documentation/devicetree/bindings/mtd/partitions/nvmem-cells.yaml /home/mwalle/repos/b-linux-arm64/Documentation/devicetree/bindings/mtd/mtd.example.dt.yaml: otp-1: compatible: ['factory-otp', 'nvmem-cells'] is too long From schema: /home/mwalle/repos/linux-mw/Documentation/devicetree/bindings/mtd/partitions/nvmem-cells.yaml /home/mwalle/repos/b-linux-arm64/Documentation/devicetree/bindings/mtd/mtd.example.dt.yaml: otp-1: compatible: Additional items are not allowed ('nvmem-cells' was unexpected) From schema: /home/mwalle/repos/linux-mw/Documentation/devicetree/bindings/mtd/partitions/nvmem-cells.yaml

Is there a way around that?


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