linux-kernel - Re: [v2 1/2] dt-bindings: Add bindings for aspeed pwm-tach and pwm.

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Message-ID: <20210414221553.GA56046@robh.at.kernel.org>
Date:   Wed, 14 Apr 2021 17:15:53 -0500
From:   Rob Herring <robh@...nel.org>
To:     Billy Tsai <billy_tsai@...eedtech.com>
Cc:     lee.jones@...aro.org, joel@....id.au, andrew@...id.au,
        thierry.reding@...il.com, u.kleine-koenig@...gutronix.de,
        p.zabel@...gutronix.de, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-pwm@...r.kernel.org, BMC-SW@...eedtech.com
Subject: Re: [v2 1/2] dt-bindings: Add bindings for aspeed pwm-tach and pwm.

On Wed, Apr 14, 2021 at 06:49:38PM +0800, Billy Tsai wrote:
> This patch adds device bindings for aspeed pwm-tach device which is a
> multi-function device include pwn and tach function and pwm device which
> should be the sub-node of pwm-tach device.
> 
> Signed-off-by: Billy Tsai <billy_tsai@...eedtech.com>
> Change-Id: I18d9dea14c3a04e1b7e38ffecd49d45917b9b545

Drop

> ---
>  .../bindings/mfd/aspeed,ast2600-pwm-tach.yaml | 60 +++++++++++++++++++
>  .../bindings/pwm/aspeed,ast2600-pwm.yaml      | 44 ++++++++++++++
>  2 files changed, 104 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
>  create mode 100644 Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml
> 
> diff --git a/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
> new file mode 100644
> index 000000000000..eaf8bdf8d44e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
> @@ -0,0 +1,60 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (C) 2021 ASPEED, Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mfd/aspeed,ast2600-pwm-tach.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: PWM Tach controller Device Tree Bindings
> +
> +description: |
> +  The PWM Tach controller is represented as a multi-function device which
> +  includes:
> +    PWM
> +    Tach

But is it really? A PWM and tach sounds like a fan controller. Look at 
other existing PWM+tach bindings we have for fans.

> +
> +maintainers:
> +  - Billy Tsai <billy_tsai@...eedtech.com>
> +
> +properties:
> +  compatible:
> +    items:
> +      - enum:
> +          - aspeed,ast2600-pwm-tach
> +      - const: syscon
> +      - const: simple-mfd
> +  reg:
> +    maxItems: 1
> +  "#address-cells":
> +    const: 1
> +  "#size-cells":
> +    const: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - "#address-cells"
> +  - "#size-cells"
> +
> +additionalProperties:
> +  type: object

As you know the 2 node names, they should be documented. However, see 
below.

> +
> +examples:
> +  - |
> +    pwm_tach: pwm_tach@...10000 {
> +      compatible = "aspeed,ast2600-pwm-tach", "syscon", "simple-mfd";
> +      #address-cells = <1>;
> +      #size-cells = <1>;
> +      reg = <0x1e610000 0x100>;
> +
> +      pwm: pwm@0 {
> +        compatible = "aspeed,ast2600-pwm";
> +        #pwm-cells = <3>;
> +        reg = <0x0 0x100>;
> +      };
> +
> +      tach: tach@1 {
> +        compatible = "aspeed,ast2600-tach";
> +        reg = <0x0 0x100>;

You have 2 nodes at the same address. Not valid.

> +      };

There's no real need for 2 child nodes. The parent node can be a PWM 
provider.

> +    };
> diff --git a/Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml b/Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml
> new file mode 100644
> index 000000000000..97923e68ccb9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml
> @@ -0,0 +1,44 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (C) 2021 ASPEED, Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pwm/aspeed,ast2600-pwm.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: ASPEED AST2600 PWM controller
> +
> +maintainers:
> +  - Billy Tsai <billy_tsai@...eedtech.com>
> +
> +description: |
> +  The ASPEED PWM controller can support upto 16 PWM outputs.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - aspeed,ast2600-pwm
> +
> +  "#pwm-cells":
> +    const: 3
> +
> +  reg:
> +    maxItems: 1
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    // The PWM should be a subnode of a "aspeed,ast2600-pwm-tach" compatible
> +    // node.
> +    pwm_tach: pwm_tach@...10000 {
> +      compatible = "aspeed,ast2600-pwm-tach", "syscon", "simple-mfd";
> +      #address-cells = <1>;
> +      #size-cells = <1>;
> +      reg = <0x1e610000 0x100>;
> +
> +      pwm: pwm@0 {
> +        compatible = "aspeed,ast2600-pwm";
> +        #pwm-cells = <3>;
> +        reg = <0x0 0x100>;
> +      };
> +    };
> -- 
> 2.25.1
>