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Date:   Wed, 2 Mar 2022 15:59:25 -0600
From:   Rob Herring <robh@kernel.org>
To:     =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= <zajec5@gmail.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        linux-mtd@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, Tom Rini <trini@konsulko.com>,
        Ricardo Salveti <ricardo@foundries.io>,
        Michal Simek <michal.simek@xilinx.com>,
        Jorge Ramirez-Ortiz <jorge@foundries.io>,
        Sean Anderson <seanga2@gmail.com>, u-boot@lists.denx.de,
        =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= <rafal@milecki.pl>
Subject: Re: [PATCH] dt-bindings: mtd: partitions: add UBI binding
Message-ID: <Yh/ovYMV104jc+CE@robh.at.kernel.org>
References: <20220217102448.27586-1-zajec5@gmail.com>
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On Thu, Feb 17, 2022 at 11:24:48AM +0100, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> UBI is often used on embedded devices to store UBI volumes with device
> configuration / calibration data. Such volumes may need to be documented
> and referenced for proper boot & setup.
> 
> Some examples:
> 1. U-Boot environment variables
> 2. Device calibration data
> 3. Default setup (e.g. initial password)
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
>  .../bindings/mtd/partitions/ubi.yaml          | 67 +++++++++++++++++++
>  1 file changed, 67 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/partitions/ubi.yaml
> 
> diff --git a/Documentation/devicetree/bindings/mtd/partitions/ubi.yaml b/Documentation/devicetree/bindings/mtd/partitions/ubi.yaml
> new file mode 100644
> index 000000000000..cd081f06d4cb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/partitions/ubi.yaml
> @@ -0,0 +1,67 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mtd/partitions/ubi.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: UBI (Unsorted Block Images) device
> +
> +description: |
> +  UBI is a layer providing logical volumes (consisting of logical blocks) on top
> +  of raw flash devices. It deals with low-level flash issues (bit-flips, bad
> +  physical eraseblocks, wearing) providing a reliable data storage.
> +
> +  UBI device is built and stored in a single flash partition.
> +
> +  Some (usually embedded) devices use UBI volumes of specific names or indexes
> +  to store setup / configuration data. This binding allows describing such
> +  volumes so they can be identified and referenced by consumers.
> +
> +maintainers:
> +  - Rafał Miłecki <rafal@milecki.pl>
> +
> +allOf:
> +  - $ref: partition.yaml#
> +
> +properties:
> +  compatible:
> +    const: ubi
> +
> +patternProperties:
> +  "^volume-[0-9a-f]+$":
> +    type: object
> +    description: UBI volume
> +    properties:
> +      volume-name:
> +        $ref: /schemas/types.yaml#/definitions/string
> +      volume-id:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +    anyOf:
> +      - required:
> +          - volume-name
> +      - required:
> +          - volume-id
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    partitions {
> +        compatible = "fixed-partitions";
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +
> +        partition@0 {
> +            compatible = "ubi";
> +            reg = <0x0000000 0x1000000>;
> +            label = "filesystem";
> +
> +            env: volume-0 {
> +                volume-name = "u-boot-env";

Why not do 'compatible = "u-boot,env";' to align with normal partitions?

Or 'label'?

We have enough ways to identify things, I don't think we need another.

> +            };
> +
> +            calibration: volume-1 {

Are 0 and 1 meaningful or just made up indexing?

> +                volume-id = <99>;
> +            };
> +        };
> +    };
> -- 
> 2.34.1
> 
>