Re: [PATCH v4 1/2] dt-bindings: mtd: partitions: Document new dynamic-partition nodes

[Rob Herring <robh@kernel.org>]

On Sat, Jun 04, 2022 at 12:57:58AM +0200, Ansuel Smith wrote:
> On Wed, Jun 01, 2022 at 04:06:55PM -0500, Rob Herring wrote:
> > On Thu, May 19, 2022 at 01:32:57AM +0200, Ansuel Smith wrote:
> > > Document new dynamic-partition 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 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@gmail.com>
> > > ---
> > >  .../mtd/partitions/dynamic-partition.yaml     | 57 +++++++++++++++++++
> > >  .../mtd/partitions/qcom,smem-part.yaml        |  4 ++
> > >  2 files changed, 61 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/mtd/partitions/dynamic-partition.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/mtd/partitions/dynamic-partition.yaml b/Documentation/devicetree/bindings/mtd/partitions/dynamic-partition.yaml
> > > new file mode 100644
> > > index 000000000000..f57d7b9cae7f
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/mtd/partitions/dynamic-partition.yaml
> > > @@ -0,0 +1,57 @@
> > > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/mtd/partitions/dynamic-partition.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Dynamic Partition
> > > +
> > > +description: |
> > > +  This binding describes a single flash partition that is dynamically allocated
> > > +  by a dedicated parser that is not a fixed-partition parser.
> > > +
> > > +  Each child of the parser partition node is then compared and if a match with
> > > +  the provided label is found then the OF node is assigned.
> > > +
> > > +  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@gmail.com>
> > > +
> > > +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
> > 
> > typo
> > 
> > > +      register with this OF node.
> > > +
> > > +required:
> > > +  - label
> > > +
> > > +additionalProperties: true
> > > +
> > > +examples:
> > > +  - |
> > > +    flash {
> > > +      partitions {
> > > +        compatible = "qcom,smem-part";
> > > +
> > > +        partition-art {
> > > +          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>;
> > > +          };
> > 
> > There's a problem with the schema structure for this which is a common 
> > problem where we have parent and child nodes with parent defined 
> > properties in the child nodes (label in this case). The issue is that 
> > there is not a single schema applied to the child node which contains 
> > all possible properties sub-node names. This is necessary to check for 
> > extra, undocumented properties using unevaluatedProperties. The creation 
> > of spi-periphera-props.yaml is an example of how to address this. I 
> > suspect that all the partition schemas may need similar restructuring.
> > 
> > The nvmem-cells schema may happen to already have 'label', so it happens 
> > to work (that and unevaluatedProperties is probably missing in places).
> > 
> > Given this schema is really just one property which is already 
> > documented for 'partition' nodes, all we really need is to say is if 
> > 'reg' is not present, then 'label' is required:
> > 
> > if:
> >   not:
> >     required: [ reg ]
> > then:
> >   required: [ label ]
> > 
> >
> 
> Just to make sure. The correct way to implement this would be drop the
> current dynamic-partition schema and expand the partition.yaml with the
> additional if and the extra stuff in the description.
> Wanted to keep the 2 thing separated but if necessary I will follow this
> path.

Yes. I agree separate would have been nice documentation wise, 
but the schema has ended having such a small difference it doesn't 
make sense anymore.

Rob

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