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From:   Jerome Brunet <jbrunet@baylibre.com>
To:     neil.armstrong@linaro.org
Cc:     Jerome Brunet <jbrunet@baylibre.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Kevin Hilman <khilman@baylibre.com>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-amlogic@lists.infradead.org, linux-pwm@vger.kernel.org,
        JunYi Zhao <junyi.zhao@amlogic.com>,
        Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>
Subject: Re: [PATCH v3 2/4] dt-bindings: pwm: amlogic: add new compatible
 for meson8 pwm type
Date:   Wed, 29 Nov 2023 17:26:35 +0100
In-reply-to: <8e78be99-3d4d-4f79-9791-404e60bcb67c@linaro.org>
Message-ID: <1jfs0ojz1a.fsf@starbuckisacylon.baylibre.com>
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On Wed 29 Nov 2023 at 17:20, Neil Armstrong <neil.armstrong@linaro.org> wrote:

> 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@baylibre.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

The complain on v2 was that it was not clear the new binding was making
the old one obsolete. It looked to me that the deprecation old bindings
needed to go together with the introduction of the new.

I don't mind one way or the other

Is there a rule somewhere about this ?

>
>> +      - 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

It's a mistake. It should not have been added to begin with in
the first patch. "amlogic,meson-gx-*" must go along with
"amlogic,meson-gxbb-*" so it matches correctly without it.

I'll fix it

>
>>       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@2000 {
>> +      compatible = "amlogic,meson8-pwm-v2";
>> +      reg = <0x1000 0x10>;
>> +      clocks = <&xtal>, <0>, <&fdiv4>, <&fdiv5>;
>> +      #pwm-cells = <3>;
>> +    };
>>     - |
>>       pwm@1000 {
>>         compatible = "amlogic,meson-s4-pwm";
>
> Neil


-- 
Jerome