Re: [RESEND PATCH v3 1/2] dt-bindings: mtd: partitions: Document new partition-dynamic nodes

[Rafał Miłecki]

On 29.04.2022 14:48, Ansuel Smith wrote:
> Document new partition-dynamic nodes used to provide an OF node for
> partition registred at runtime by parsers. This is required for nvmem
> system to declare and detect nvmem-cells.
>
> With these special partitions, the reg / offset is not required.
> The node name must be in the form of "partition name"-dynamic.
> If the partition can't be displayed using the node name, it's possible
> to use the label binding that will be used instead of the node name.
> The node name or the label binding is used to match the partition
> allocated by the parser at runtime and the parser will provide reg
> and offset of the mtd.
>
> NVMEM will use the data from the parser and provide the NVMEM cells
> declared in the DTS, "connecting" the dynamic partition with a
> static declaration of cells in them.
>
> Signed-off-by: Ansuel Smith <ansuelsmth@xxxxxxxxx>
> ---
>   .../mtd/partitions/partition-dynamic.yaml     | 56 +++++++++++++++++++
>   .../mtd/partitions/qcom,smem-part.yaml        |  4 ++
>   2 files changed, 60 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/mtd/partitions/partition-dynamic.yaml
>
> diff --git a/Documentation/devicetree/bindings/mtd/partitions/partition-dynamic.yaml b/Documentation/devicetree/bindings/mtd/partitions/partition-dynamic.yaml
> new file mode 100644
> index 000000000000..e0efa58e4fac
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/partitions/partition-dynamic.yaml
> @@ -0,0 +1,56 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mtd/partitions/partition-dynamic.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Dynamic Partition

I'm not native but that "Dynamic Partition" sounds pretty natural and
I'm wondering if you shouldn't make that binding dynamic-partition.yaml

Any natives to comment on this? :)


> +description: |
> +  This binding describes a single flash partition that is dynamically allocated
> +  by a dedicated parser that is not a fixed-partition parser.
> +
> +  A dynamic partition require the node ending with the "-dynamic" tag and if the
> +  dynamic partition name can't be displayed using the node name, the label
> +  properties can be used. The node name or the label have to match the dynamic
> +  partition allocated by the parser.
> +
> +  These special partition definition can be used to give a dynamic partition
> +  an OF node to declare NVMEM cells. An example is declaring the partition
> +  label and all the NVMEM cells in it. The parser will detect the correct reg
> +  and offset and the NVMEM will register the cells in it based on the data
> +  extracted by the parser.
> +
> +maintainers:
> +  - Ansuel Smith <ansuelsmth@xxxxxxxxx>
> +
> +properties:
> +  label:
> +    description: The label / name for the partition assigned by the parser at
> +      runtime. This is needed for sybsystem like NVMEM to define cells and
> +      register with this OF node.
> +
> +additionalProperties: true
> +
> +examples:
> +  - |
> +    flash {
> +      partitions {
> +        compatible = "qcom,smem-part";
> +
> +        art-dynamic {
> +          compatible = "nvmem-cells";
> +          #address-cells = <1>;
> +          #size-cells = <1>;
> +          label = "0:art";
> +
> +          macaddr_art_0: macaddr@0 {
> +            reg = <0x0 0x6>;
> +          };
> +
> +          macaddr_art_6: macaddr@6 {
> +            reg = <0x6 0x6>;
> +          };
> +        };
> +      };
> +    };

I see that we need a property (like "label") for storing partition name
as it may contain characters not allowed in $nodename.

Is there a reason to play with all that foo-dynamic $nodename then? With
fallback from "label" to extracting foo from *-dynamic pattern?

Could we just be lazy, keep things simple and require "label" property?

Then we could e.g. require $nodename to be pattern ^partition-[0-9a-f]+$
It's what leds-gpio.yaml does for reference.

Example:

partitions {
	compatible = "foo";

	partition-1 {
		label = "bootloader";
	};

	partition-2 {
		label = "0:art";
	};
};