Re: [PATCH v2 1/3] dt-bindings: pwm: amlogic: Add core clock for T7

[linux-kernel-dev]

On 9/26/26 8:06 PM, Conor Dooley wrote:
> On Sat, Sep 26, 2026 at 11:43:20AM +0200, linux-kernel-dev@xxxxxxxx wrote:
>> On 9/25/26 6:41 PM, Conor Dooley wrote:
>>> On Fri, Sep 25, 2026 at 05:13:28PM +0200, Ronald Claveau via B4 Relay wrote:
>>>> From: Ronald Claveau <linux-kernel-dev@xxxxxxxx>
>>>>
>>>> The T7, A1, C3, and S4 PWM controllers have a system clock in
>>>> addition to the two input clocks of channels A and B.
>>>>
>>>> The channel clocks are acquired by index in the pwm driver,
>>>> where the core clock is fetched by name, with optional get
>>>> which is silent when not provided.
>>>>
>>>> Require clock-names and minimum 3 items for T7, where the
>>>> PWM devices do not work without all 3 clocks.
>>>>
>>>> Add an example showing T7 usage with its fallback to
>>>> amlogic,meson-s4-pwm.
>>>>
>>>> Signed-off-by: Ronald Claveau <linux-kernel-dev@xxxxxxxx>
>>>> ---
>>>>  .../devicetree/bindings/pwm/pwm-amlogic.yaml       | 33 ++++++++++++++++++++--
>>>>  1 file changed, 31 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
>>>> index c337d85da40f1..59320f288552b 100644
>>>> --- a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
>>>> +++ b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
>>>> @@ -62,7 +62,7 @@ properties:
>>>>  
>>>>    clock-names:
>>>>      minItems: 1
>>>> -    maxItems: 2
>>>> +    maxItems: 3
>>>>  
>>>>    power-domains:
>>>>      maxItems: 1
>>>> @@ -140,13 +140,34 @@ allOf:
>>>>      then:
>>>>        properties:
>>>>          clocks:
>>>> +          minItems: 2
>>>>            items:
>>>>              - description: input clock of PWM channel A
>>>>              - description: input clock of PWM channel B
>>>> -        clock-names: false
>>>> +            - description: gate clock for the PWM controller
>>>> +        clock-names:
>>>> +          minItems: 2
>>>> +          items:
>>>> +            - const: channel-a
>>>> +            - const: channel-b
>>>> +            - const: core
>>>>        required:
>>>>          - clocks
>>>>  
>>>> +  - if:
>>>> +      properties:
>>>> +        compatible:
>>>> +          contains:
>>>> +            const: amlogic,t7-pwm
>>>
>>> Shouldn't this (based on your reply on the previous version) be s4?
>>>
>>
>> The change above is for S4 and SOCs which fallback to S4. It allows the
>> third clock but let the schema validation compatible with two clocks
>> existing DTS. Here for the T7, I add requirement for the exact 3 clocks.
>>
>> Do you recommend to require the 3 clocks for all S4 and S4 fallback, and
>> update the associated dtsi files ?
> 
> Yes, I think so. Sounds to me like they only work because of the
> CLK_IGNORE_UNUSED set in their clock controller drivers, so the correct
> thing to do is make them all require the third clock.
> 

Great, Thank you for your feedback, I sent a V3 matching this.

>>
>>>> +    then:
>>>> +      properties:
>>>> +        clocks:
>>>> +          minItems: 3
>>>> +        clock-names:
>>>> +          minItems: 3
>>>> +      required:
>>>> +        - clock-names
>>>> +
>>>>    - if:
>>>>        properties:
>>>>          compatible:
>>>> @@ -182,3 +203,11 @@ examples:
>>>>        clocks = <&pwm_src_a>, <&pwm_src_b>;
>>>>        #pwm-cells = <3>;
>>>>      };
>>>> +  - |
>>>> +    pwm@60000 {
>>>> +      compatible = "amlogic,t7-pwm", "amlogic,meson-s4-pwm";
>>>> +      reg = <0x60000 0x24>;
>>>> +      clocks = <&channel_a>, <&channel_b>, <&core>;
>>>> +      clock-names = "channel-a", "channel-b", "core";
>>>> +      #pwm-cells = <3>;
>>>> +    };
>>>>
>>>> -- 
>>>> 2.49.0
>>>>
>>>>
>>
>>
>> -- 
>> Best regards,
>> Ronald


-- 
Best regards,
Ronald