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From: Simon Glass <sjg@chromium.org>
Date: Thu, 14 Dec 2023 14:09:24 -0700
Message-ID: <CAPnjgZ2oJSGPO91Y_aLbe+v250WFrND4n3T0mOvhERYidVu=eQ@mail.gmail.com>
Subject: Re: [PATCH v6 1/3] dt-bindings: mtd: partitions: Add binman compatible
To: Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org, Miquel Raynal <miquel.raynal@bootlin.com>, 
	linux-mtd@lists.infradead.org, Tom Rini <trini@konsulko.com>, 
	Michael Walle <mwalle@kernel.org>, U-Boot Mailing List <u-boot@lists.denx.de>, 
	Conor Dooley <conor+dt@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Pratyush Yadav <ptyadav@amazon.de>, 
	=?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <rafal@milecki.pl>, 
	Richard Weinberger <richard@nod.at>, Vignesh Raghavendra <vigneshr@ti.com>, linux-kernel@vger.kernel.org
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Hi Rob,

On Thu, 14 Dec 2023 at 10:27, Rob Herring <robh@kernel.org> wrote:
>
> On Fri, Dec 08, 2023 at 03:58:10PM -0700, Simon Glass wrote:
> > Hi Rob,
> >
> > On Fri, 8 Dec 2023 at 14:56, Rob Herring <robh@kernel.org> wrote:
> > >
> > > On Fri, Dec 8, 2023 at 11:47=E2=80=AFAM Simon Glass <sjg@chromium.org=
> wrote:
> > > >
> > > > Hi Rob,
> > > >
> > > > On Fri, 8 Dec 2023 at 08:00, Rob Herring <robh@kernel.org> wrote:
> > > > >
> > > > > On Thu, Nov 16, 2023 at 10:28:50AM -0700, Simon Glass wrote:
> > > > > > Add a compatible string for binman, so we can extend fixed-part=
itions
> > > > > > in various ways.
> > > > > >
> > > > > > Signed-off-by: Simon Glass <sjg@chromium.org>
> > > > > > ---
> > > > > >
> > > > > > (no changes since v5)
> > > > > >
> > > > > > Changes in v5:
> > > > > > - Add #address/size-cells and parternProperties
> > > > > > - Drop $ref to fixed-partitions.yaml
> > > > > > - Drop 'select: false'
> > > > > >
> > > > > > Changes in v4:
> > > > > > - Change subject line
> > > > > >
> > > > > > Changes in v3:
> > > > > > - Drop fixed-partition additional compatible string
> > > > > > - Drop fixed-partitions from the example
> > > > > > - Mention use of compatible instead of label
> > > > > >
> > > > > > Changes in v2:
> > > > > > - Drop mention of 'enhanced features' in fixed-partitions.yaml
> > > > > > - Mention Binman input and output properties
> > > > > > - Use plain partition@xxx for the node name
> > > > > >
> > > > > >  .../bindings/mtd/partitions/binman.yaml       | 68 +++++++++++=
++++++++
> > > > > >  .../bindings/mtd/partitions/partitions.yaml   |  1 +
> > > > > >  MAINTAINERS                                   |  5 ++
> > > > > >  3 files changed, 74 insertions(+)
> > > > > >  create mode 100644 Documentation/devicetree/bindings/mtd/parti=
tions/binman.yaml
> > > > > >
> > > > > > diff --git a/Documentation/devicetree/bindings/mtd/partitions/b=
inman.yaml b/Documentation/devicetree/bindings/mtd/partitions/binman.yaml
> > > > > > new file mode 100644
> > > > > > index 000000000000..329217550a98
> > > > > > --- /dev/null
> > > > > > +++ b/Documentation/devicetree/bindings/mtd/partitions/binman.y=
aml
> > > > > > @@ -0,0 +1,68 @@
> > > > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > > > +# Copyright 2023 Google LLC
> > > > > > +
> > > > > > +%YAML 1.2
> > > > > > +---
> > > > > > +$id: http://devicetree.org/schemas/mtd/partitions/binman.yaml#
> > > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > > > +
> > > > > > +title: Binman firmware layout
> > > > > > +
> > > > > > +maintainers:
> > > > > > +  - Simon Glass <sjg@chromium.org>
> > > > > > +
> > > > > > +description: |
> > > > > > +  The binman node provides a layout for firmware, used when pa=
ckaging firmware
> > > > > > +  from multiple projects. It is based on fixed-partitions, wit=
h some
> > > > > > +  extensions, but uses 'compatible' to indicate the contents o=
f the node, to
> > > > > > +  avoid perturbing or confusing existing installations which u=
se 'label' for a
> > > > > > +  particular purpose.
> > > > > > +
> > > > > > +  Binman supports properties used as inputs to the firmware-pa=
ckaging process,
> > > > > > +  such as those which control alignment of partitions. This bi=
nding addresses
> > > > > > +  these 'input' properties. For example, it is common for the =
'reg' property
> > > > > > +  (an 'output' property) to be set by Binman, based on the ali=
gnment requested
> > > > > > +  in the input.
> > > > > > +
> > > > > > +  Once processing is complete, input properties have mostly se=
rved their
> > > > > > +  purpose, at least until the firmware is repacked later, e.g.=
 due to a
> > > > > > +  firmware update. The 'fixed-partitions' binding should provi=
de enough
> > > > > > +  information to read the firmware at runtime, including decom=
pression if
> > > > > > +  needed.
> > > > >
> > > > > How is this going to work exactly? binman reads these nodes and t=
hen
> > > > > writes out 'fixed-partitions' nodes. But then you've lost the bin=
man
> > > > > specifc parts needed for repacking.
> > > >
> > > > No, they are the same node. I do want the extra information to stic=
k
> > > > around. So long as it is compatible with fixed-partition as well, t=
his
> > > > should work OK.
> > >
> > > How can it be both? The partitions node compatible can be either
> > > 'fixed-partitions' or 'binman'.
> >
> > Can we not allow it to be both? I have tried to adjust things in
> > response to feedback but perhaps the feedback was leading me down the
> > wrong path?
>
> Sure, but then the schema has to and that means extending
> fixed-partitions.

Can we cross that bridge later? There might be resistance to it. I'm
not sure. For now, perhaps just a binman compatible works well enough
to make progress.

Regards,
Simon