linux-kernel - Re: [PATCH v5 1/3] dt-bindings: mtd: partitions: Support label only partition

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Date:   Thu, 9 Jun 2022 12:32:52 -0600
From:   Rob Herring <robh@...nel.org>
To:     Ansuel Smith <ansuelsmth@...il.com>
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>,
        Jens Axboe <axboe@...nel.dk>,
        �ecki <rafal@...ecki.pl>,
        Manivannan Sadhasivam <mani@...nel.org>,
        linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/3] dt-bindings: mtd: partitions: Support label only
 partition

On Mon, Jun 06, 2022 at 05:14:15PM +0200, Ansuel Smith wrote:
> Document new partition nodes that declare only the label instead of the
> reg 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>
> ---
>  .../bindings/mtd/partitions/partition.yaml       | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/partitions/partition.yaml b/Documentation/devicetree/bindings/mtd/partitions/partition.yaml
> index e1ac08064425..bff6fb980e6b 100644
> --- a/Documentation/devicetree/bindings/mtd/partitions/partition.yaml
> +++ b/Documentation/devicetree/bindings/mtd/partitions/partition.yaml
> @@ -11,6 +11,13 @@ description: |
>    relative offset and size specified. Depending on partition function extra
>    properties can be used.
>  
> +  A partition may be dynamically allocated by a specific parser at runtime.
> +  In this specific case, the label is required instead of the reg.
> +  This is used to assign an OF node to the dynamiccally allocated partition
> +  so that subsystem like NVMEM can provide an OF node and declare NVMEM cells.
> +  The OF node will be assigned only if the partition label declared match the
> +  one assigned by the parser at runtime.
> +
>  maintainers:
>    - Rafał Miłecki <rafal@...ecki.pl>
>  
> @@ -22,6 +29,8 @@ properties:
>    label:
>      description: The label / name for this partition. If omitted, the label
>        is taken from the node name (excluding the unit address).
> +      With dynamically allocated partition the label is required and won't
> +      fallback to the node name.

Generally, label is never required being something for humans rather 
than the s/w to consume. I don't see any reason why we can't still use 
the node name (with 'partition-' stripped off).

If the purpose is to define what the partition contains, then 
'compatible' is the right thing for that.

>  
>    read-only:
>      description: This parameter, if present, is a hint that this partition
> @@ -41,7 +50,10 @@ properties:
>        immune to paired-pages corruptions
>      type: boolean
>  
> -required:
> -  - reg
> +if:
> +  not:
> +    required: [ reg ]
> +then:
> +  required: [ label ]
>  
>  additionalProperties: true
> -- 
> 2.36.1
> 
>