Message-ID: <629a91f8.1c69fb81.371aa.1d32@mx.google.com>
Date:   Sat, 4 Jun 2022 00:57:58 +0200
From:   Ansuel Smith <ansuelsmth@...il.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] dt-bindings: mtd: partitions: Document new
 dynamic-partition nodes

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@...il.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@...il.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.

> > +        };
> > +      };
> > +    };
> > diff --git a/Documentation/devicetree/bindings/mtd/partitions/qcom,smem-part.yaml b/Documentation/devicetree/bindings/mtd/partitions/qcom,smem-part.yaml
> > index cf3f8c1e035d..b6fa25949fe2 100644
> > --- a/Documentation/devicetree/bindings/mtd/partitions/qcom,smem-part.yaml
> > +++ b/Documentation/devicetree/bindings/mtd/partitions/qcom,smem-part.yaml
> > @@ -19,6 +19,10 @@ properties:
> >    compatible:
> >      const: qcom,smem-part
> >  
> > +patternProperties:
> > +  "^partition-[0-9a-z]+$":
> > +    $ref: dynamic-partition.yaml#
> > +
> >  required:
> >    - compatible
> >  
> > -- 
> > 2.34.1
> > 
> > 

-- 
	Ansuel

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