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

[Rob Herring]

On Fri, Dec 8, 2023 at 11:47 AM Simon Glass <sjg@xxxxxxxxxxxx> wrote:
>
> Hi Rob,
>
> On Fri, 8 Dec 2023 at 08:00, Rob Herring <robh@xxxxxxxxxx> 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@xxxxxxxxxxxx>
> > > ---
> > >
> > > (no changes since v5)
> > >
> > > Changes in v5:
> > > - Add #address/size-cells and parternProperties
> > > - Drop $ref to fixed-partitions.yaml
> > > - Drop 'select: false'
> > >
> > > Changes in v4:
> > > - Change subject line
> > >
> > > Changes in v3:
> > > - Drop fixed-partition additional compatible string
> > > - Drop fixed-partitions from the example
> > > - Mention use of compatible instead of label
> > >
> > > Changes in v2:
> > > - Drop mention of 'enhanced features' in fixed-partitions.yaml
> > > - Mention Binman input and output properties
> > > - Use plain partition@xxx for the node name
> > >
> > >  .../bindings/mtd/partitions/binman.yaml       | 68 +++++++++++++++++++
> > >  .../bindings/mtd/partitions/partitions.yaml   |  1 +
> > >  MAINTAINERS                                   |  5 ++
> > >  3 files changed, 74 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/mtd/partitions/binman.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/mtd/partitions/binman.yaml b/Documentation/devicetree/bindings/mtd/partitions/binman.yaml
> > > new file mode 100644
> > > index 000000000000..329217550a98
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/mtd/partitions/binman.yaml
> > > @@ -0,0 +1,68 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +# Copyright 2023 Google LLC
> > > +
> > > +%YAML 1.2
> > > +---
> > > +$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@xxxxxxxxxxxx>
> > > +
> > > +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'.

In the partition nodes, 'align' for example is allowed for a binman
partition but not a fixed-partition.

Note that the schema may not actually warn on extra properties ATM
because there are some issues with the schema structure. Since there
can be nested partittions, that complicates matters. It's been on my
todo list to fix.


Rob