[PATCH v6 1/3] dt-bindings: mtd: partitions: Add binman compatible

[Rob Herring]

On Thu, Jan 4, 2024 at 3:54 PM Simon Glass <sjg at chromium.org> wrote:
>
> Hi Rob,
>
> On Thu, Dec 14, 2023 at 2:09 PM Simon Glass <sjg at chromium.org> wrote:
> >
> > Hi Rob,
> >
> > On Thu, 14 Dec 2023 at 10:27, Rob Herring <robh at 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 at kernel.org> wrote:
> > > > >
> > > > > On Fri, Dec 8, 2023 at 11:47 AM Simon Glass <sjg at chromium.org> wrote:
> > > > > >
> > > > > > Hi Rob,
> > > > > >
> > > > > > On Fri, 8 Dec 2023 at 08:00, Rob Herring <robh at 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-partitions
> > > > > > > > in various ways.
> > > > > > > >
> > > > > > > > Signed-off-by: Simon Glass <sjg at chromium.org>
> > > > > > > > ---
> > > > > > > >
> > > > > > > > (no changes since v5)
> > > > > > > >
> > > > > > > > Changes in v5:
> > > > > > > > - Add #address/size-cells and parternProperties
> > > > > > > > - Drop $ref to fixed-partitions.yaml
> > > > > > > > - Drop 'select: false'
> > > > > > > >
> > > > > > > > Changes in v4:
> > > > > > > > - Change subject line
> > > > > > > >
> > > > > > > > Changes in v3:
> > > > > > > > - Drop fixed-partition additional compatible string
> > > > > > > > - Drop fixed-partitions from the example
> > > > > > > > - Mention use of compatible instead of label
> > > > > > > >
> > > > > > > > Changes in v2:
> > > > > > > > - Drop mention of 'enhanced features' in fixed-partitions.yaml
> > > > > > > > - Mention Binman input and output properties
> > > > > > > > - Use plain partition at xxx for the node name
> > > > > > > >
> > > > > > > >  .../bindings/mtd/partitions/binman.yaml       | 68 +++++++++++++++++++
> > > > > > > >  .../bindings/mtd/partitions/partitions.yaml   |  1 +
> > > > > > > >  MAINTAINERS                                   |  5 ++
> > > > > > > >  3 files changed, 74 insertions(+)
> > > > > > > >  create mode 100644 Documentation/devicetree/bindings/mtd/partitions/binman.yaml
> > > > > > > >
> > > > > > > > diff --git a/Documentation/devicetree/bindings/mtd/partitions/binman.yaml b/Documentation/devicetree/bindings/mtd/partitions/binman.yaml
> > > > > > > > new file mode 100644
> > > > > > > > index 000000000000..329217550a98
> > > > > > > > --- /dev/null
> > > > > > > > +++ b/Documentation/devicetree/bindings/mtd/partitions/binman.yaml
> > > > > > > > @@ -0,0 +1,68 @@
> > > > > > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > > > > > +# Copyright 2023 Google LLC
> > > > > > > > +
> > > > > > > > +%YAML 1.2
> > > > > > > > +---
> > > > > > > > +$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 at chromium.org>
> > > > > > > > +
> > > > > > > > +description: |
> > > > > > > > +  The binman node provides a layout for firmware, used when packaging firmware
> > > > > > > > +  from multiple projects. It is based on fixed-partitions, with some
> > > > > > > > +  extensions, but uses 'compatible' to indicate the contents of the node, to
> > > > > > > > +  avoid perturbing or confusing existing installations which use 'label' for a
> > > > > > > > +  particular purpose.
> > > > > > > > +
> > > > > > > > +  Binman supports properties used as inputs to the firmware-packaging process,
> > > > > > > > +  such as those which control alignment of partitions. This binding addresses
> > > > > > > > +  these 'input' properties. For example, it is common for the 'reg' property
> > > > > > > > +  (an 'output' property) to be set by Binman, based on the alignment requested
> > > > > > > > +  in the input.
> > > > > > > > +
> > > > > > > > +  Once processing is complete, input properties have mostly served their
> > > > > > > > +  purpose, at least until the firmware is repacked later, e.g. due to a
> > > > > > > > +  firmware update. The 'fixed-partitions' binding should provide enough
> > > > > > > > +  information to read the firmware at runtime, including decompression if
> > > > > > > > +  needed.
> > > > > > >
> > > > > > > How is this going to work exactly? binman reads these nodes and then
> > > > > > > writes out 'fixed-partitions' nodes. But then you've lost the binman
> > > > > > > specifc parts needed for repacking.
> > > > > >
> > > > > > No, they are the same node. I do want the extra information to stick
> > > > > > around. So long as it is compatible with fixed-partition as well, this
> > > > > > 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.
>
> Is there any way to make progress on this? I would like to have
> software which doesn't understand the binman compatible to at least be
> able to understand the fixed-partition compatible. Is that acceptable?

There's only 2 ways that it can work. Either binman writes out
fixed-partition nodes dropping/replacing anything only defined for
binman or fixed-partition is extended to include what binman needs.

Rob