Date:   Wed, 29 Nov 2023 17:20:51 +0100
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     Kevin Hilman <khilman@...libre.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-amlogic@...ts.infradead.org,
        linux-pwm@...r.kernel.org, JunYi Zhao <junyi.zhao@...ogic.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH v3 2/4] dt-bindings: pwm: amlogic: add new compatible for
 meson8 pwm type

Hi,

On 29/11/2023 14:39, Jerome Brunet wrote:
> Add a new compatible for the pwm found in the meson8 to sm1 Amlogic SoCs,
> dealing with clocks differently. This does not enable new HW. It is meant
> to fix a bad DT ABI for the currently supported HW.
> 
> The original clock bindings describe which input the PWM channel
> multiplexer should pick among its possible parents, which are
> hard-coded in the driver. As such, it is a setting tied to the driver
> implementation and does not describe the HW.
> 
> The new bindings introduce here describe the clocks input of the PWM block
> as they exist.
> 
> The old compatible is deprecated but kept to maintain ABI compatibility.
> 
> The SoC specific compatibles introduced match the SoC families supported
> by the original bindings.
> 
> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
> ---
>   .../devicetree/bindings/pwm/pwm-amlogic.yaml  | 52 ++++++++++++++++---
>   1 file changed, 46 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
> index 387976ed36d5..eece390114a3 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
> +++ b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
> @@ -21,23 +21,35 @@ properties:
>             - amlogic,meson-g12a-ee-pwm
>             - amlogic,meson-g12a-ao-pwm-ab
>             - amlogic,meson-g12a-ao-pwm-cd
> -          - amlogic,meson-s4-pwm
> +        deprecated: true
>         - items:
>             - const: amlogic,meson-gx-pwm
>             - const: amlogic,meson-gxbb-pwm
> +        deprecated: true
>         - items:
>             - const: amlogic,meson-gx-ao-pwm
>             - const: amlogic,meson-gxbb-ao-pwm
> +        deprecated: true
>         - items:
>             - const: amlogic,meson8-pwm
>             - const: amlogic,meson8b-pwm
> +        deprecated: true

I think deprecated should be moved in a third patch

> +      - const: amlogic,meson8-pwm-v2
> +      - items:
> +          - enum:
> +              - amlogic,meson8b-pwm-v2
> +              - amlogic,meson-gxbb-pwm-v2
> +              - amlogic,meson-axg-pwm-v2
> +              - amlogic,meson-g12-pwm-v2
> +          - const: amlogic,meson8-pwm-v2
> +      - const: amlogic,meson-s4-pwm
>   
>     reg:
>       maxItems: 1
>   
>     clocks:
>       minItems: 1
> -    maxItems: 2
> +    maxItems: 4
>   
>     clock-names:
>       minItems: 1
> @@ -58,7 +70,6 @@ allOf:
>           compatible:
>             contains:
>               enum:
> -              - amlogic,meson8-pwm
>                 - amlogic,meson8b-pwm
>                 - amlogic,meson-gxbb-pwm
>                 - amlogic,meson-gxbb-ao-pwm
> @@ -67,14 +78,15 @@ allOf:
>                 - amlogic,meson-g12a-ee-pwm
>                 - amlogic,meson-g12a-ao-pwm-ab
>                 - amlogic,meson-g12a-ao-pwm-cd
> -              - amlogic,meson-gx-pwm
> -              - amlogic,meson-gx-ao-pwm

I don't understand why those entries are removed

>       then:
> -      # Historic bindings tied to the driver implementation
> +      # Obsolete historic bindings tied to the driver implementation
>         # The clocks provided here are meant to be matched with the input
>         # known (hard-coded) in the driver and used to select pwm clock
>         # source. Currently, the linux driver ignores this.
> +      # This is kept to maintain ABI backward compatibility.

Same here, this should go in a third patch

>         properties:
> +        clocks:
> +          maxItems: 2
>           clock-names:
>             oneOf:
>               - items:
> @@ -83,6 +95,27 @@ allOf:
>                   - const: clkin0
>                   - const: clkin1
>   
> +  # Newer binding where clock describe the actual clock inputs of the pwm
> +  # block. These are necessary but some inputs may be grounded.
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - amlogic,meson8-pwm-v2
> +    then:
> +      properties:
> +        clocks:
> +          minItems: 1
> +          items:
> +            - description: input clock 0 of the pwm block
> +            - description: input clock 1 of the pwm block
> +            - description: input clock 2 of the pwm block
> +            - description: input clock 3 of the pwm block
> +        clock-names: false
> +      required:
> +        - clocks
> +
>     # Newer IP block take a single input per channel, instead of 4 inputs
>     # for both channels
>     - if:
> @@ -112,6 +145,13 @@ examples:
>         clock-names = "clkin0", "clkin1";
>         #pwm-cells = <3>;
>       };
> +  - |
> +    pwm@...0 {
> +      compatible = "amlogic,meson8-pwm-v2";
> +      reg = <0x1000 0x10>;
> +      clocks = <&xtal>, <0>, <&fdiv4>, <&fdiv5>;
> +      #pwm-cells = <3>;
> +    };
>     - |
>       pwm@...0 {
>         compatible = "amlogic,meson-s4-pwm";

Neil

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