linux-kernel - Re: [PATCH 2/3] dt-bindings: hwmon: g76x: Add support for g761

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Message-ID: <818aacc7-5244-45e1-844d-561e8540cb46@roeck-us.net>
Date: Sat, 25 May 2024 07:53:57 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Christian Marangi <ansuelsmth@...il.com>
Cc: Jean Delvare <jdelvare@...e.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, linux-hwmon@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: hwmon: g76x: Add support for g761

On 5/25/24 03:50, Christian Marangi wrote:
> On Sat, May 25, 2024 at 07:32:04AM -0700, Guenter Roeck wrote:
>> On 5/25/24 03:29, Christian Marangi wrote:
>>> Add support for g761 PWM Fan controller. This is an exact copy of g763
>>> with the difference that it does also support an internal clock
>>> oscillators.
>>>
>>> Add required logic to support this additional feature with the property
>>> gmt,internal-clock and reject invalid schema that define both
>>> internal-clock property and external clocks.
>>>
>>> Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
>>> ---
>>>    .../devicetree/bindings/hwmon/gmt,g76x.yaml   | 43 +++++++++++++++++--
>>>    1 file changed, 40 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/hwmon/gmt,g76x.yaml b/Documentation/devicetree/bindings/hwmon/gmt,g76x.yaml
>>> index bfefe49f54bf..d6e80392d045 100644
>>> --- a/Documentation/devicetree/bindings/hwmon/gmt,g76x.yaml
>>> +++ b/Documentation/devicetree/bindings/hwmon/gmt,g76x.yaml
>>> @@ -4,13 +4,13 @@
>>>    $id: http://devicetree.org/schemas/hwmon/gmt,g76x.yaml#
>>>    $schema: http://devicetree.org/meta-schemas/core.yaml#
>>> -title: GMT G762/G763 PWM Fan controller
>>> +title: GMT G761/G762/G763 PWM Fan controller
>>>    maintainers:
>>>      - Christian Marangi <ansuelsmth@...il.com>
>>>    description: |
>>> -  GMT G762/G763 PWM Fan controller.
>>> +  GMT G761/G762/G763 PWM Fan controller.
>>>      If an optional property is not set in DT, then current value is kept
>>>      unmodified (e.g. bootloader installed value).
>>> @@ -22,6 +22,7 @@ description: |
>>>    properties:
>>>      compatible:
>>>        enum:
>>> +      - gmt,g761
>>>          - gmt,g762
>>>          - gmt,g763
>>> @@ -48,10 +49,37 @@ properties:
>>>        $ref: /schemas/types.yaml#/definitions/uint32
>>>        enum: [0, 1, 2]
>>> +  gmt,internal-clock:
>>> +    description: Use the Internal clock instead of externally attached one
>>> +      via the CLK pin.
>>> +    type: boolean
>>> +
>>>    required:
>>>      - compatible
>>>      - reg
>>> -  - clocks
>>> +
>>> +allOf:
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            enum:
>>> +              - gmt,g762
>>> +              - gmt,g763
>>> +    then:
>>> +      properties:
>>> +        gmt,internal-clock: false
>>> +
>>> +      required:
>>> +        - clocks
>>
>> Is the new property even necessary ? The absence of an external clock on G761
>> could be used to imply that the internal clock is used.
>>
> 
> Well with how the driver works, if a property is not defined, then the
> value is not set and the one set by the bootloader or from device reset
> is keept.
> 
> This conflicts with the logic of no clock = internal.
> 

Not sure I understand the problem. It would be a simple change in the driver
to add "if the chip is G761 and the clock is not provided in DT, use the
internal clock".

Guenter