linux-kernel - Re: [PATCH 3/4] dt-bindings: memory: Add jedec,lpddr4 and jedec,lpddr5 bindings

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Message-ID: <983c1224-8174-3534-a276-d1ab1f9968a4@linaro.org>
Date:   Wed, 31 Aug 2022 09:28:53 +0300
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Julius Werner <jwerner@...omium.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Dmitry Osipenko <digetx@...il.com>,
        Doug Anderson <dianders@...omium.org>,
        Jian-Jia Su <jjsu@...gle.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] dt-bindings: memory: Add jedec,lpddr4 and
 jedec,lpddr5 bindings

On 31/08/2022 04:33, Julius Werner wrote:
> This patch adds bindings for LPDDR4 and LPDDR5 memory analogous to the
> existing bindings for LPDDR2 and LPDDR3. For now, the new types are only
> needed for topology description, so other properties like timing
> parameters are omitted. They can be added later if needed.
> 
> Signed-off-by: Julius Werner <jwerner@...omium.org>
> ---
>  .../ddr/jedec,lpddr-props.yaml                |  4 ++
>  .../memory-controllers/ddr/jedec,lpddr4.yaml  | 36 ++++++++++++++
>  .../memory-controllers/ddr/jedec,lpddr5.yaml  | 48 +++++++++++++++++++
>  3 files changed, 88 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr4.yaml
>  create mode 100644 Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr5.yaml
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr-props.yaml b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr-props.yaml
> index 0c7d2feafd77c8..e1182e75ca1a3f 100644
> --- a/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr-props.yaml
> +++ b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr-props.yaml
> @@ -53,9 +53,13 @@ properties:
>        - 512
>        - 1024
>        - 2048
> +      - 3072
>        - 4096
> +      - 6144
>        - 8192
> +      - 12288
>        - 16384
> +      - 24576
>        - 32768

Either you limit now LPDDR2 and LPDDR3 to old values or instead add this
bigger list to LPDDR4 and LPDDR5 (if it works that way).

>  
>    io-width:
> diff --git a/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr4.yaml b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr4.yaml
> new file mode 100644
> index 00000000000000..860300cebee754
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr4.yaml
> @@ -0,0 +1,36 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,lpddr4.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: LPDDR4 SDRAM compliant to JEDEC JESD209-4
> +
> +allOf:
> +  - $ref: "jedec,lpddr-props.yaml#"

allOf goes below maintainers.

> +
> +maintainers:
> +  - Krzysztof Kozlowski <krzk@...nel.org>
> +
> +properties:
> +  compatible:
> +    items:
> +      - pattern: "^lpddr4-[0-9a-f]{2},[0-9a-f]{4}$"
> +      - const: jedec,lpddr4
> +
> +required:
> +  - compatible
> +  - density
> +  - io-width
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    lpddr4 {

Let's just call it "lpddr" to be generic.

> +        compatible = "lpddr4-ff,0100", "jedec,lpddr4";
> +        density = <8192>;
> +        io-width = <16>;
> +        manufacturer-id = <255>;
> +        revision-id = <1 0>;
> +    };
> diff --git a/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr5.yaml b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr5.yaml
> new file mode 100644
> index 00000000000000..ae3894bb346d5e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr5.yaml
> @@ -0,0 +1,48 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,lpddr5.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: LPDDR5 SDRAM compliant to JEDEC JESD209-5
> +
> +allOf:
> +  - $ref: "jedec,lpddr-props.yaml#"
> +
> +maintainers:
> +  - Krzysztof Kozlowski <krzk@...nel.org>
> +
> +properties:
> +  compatible:
> +    items:
> +      - pattern: "^lpddr5-[0-9a-f]{2},[0-9a-f]{4}$"
> +      - const: jedec,lpddr5
> +
> +  serial-id:
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    description:
> +      Serial IDs read from Mode Registers 47 through 54. One byte per uint32
> +      cell (i.e. <MR47 MR48 MR49 MR50 MR51 MR52 MR53 MR54>).
> +    minItems: 8

No need for minItems.

> +    maxItems: 8
> +    items:
> +      minimum: 0
> +      maximum: 255
> +
> +required:
> +  - compatible
> +  - density
> +  - io-width
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    lpddr4 {

Let's just call it "lpddr" to be generic (it's lpddr5 anyway).

> +        compatible = "lpddr5-01,0200", "jedec,lpddr5";
> +        density = <8192>;
> +        io-width = <8>;
> +        manufacturer-id = <1>;
> +        revision-id = <2 0>;
> +        serial-id = <3 1 0 0 0 0 0 0>;
> +    };


Best regards,
Krzysztof