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

Rob Herring
2023-12-08T15:00:51Z

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

Rob