linux-kernel - Re: [PATCH v4 1/3] dt-bindings: hwmon: fan: Add fan binding to schema

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Date:   Tue, 25 Oct 2022 14:46:27 +0530
From:   Naresh Solanki <naresh.solanki@...ements.com>
To:     Rob Herring <robh@...nel.org>
Cc:     devicetree@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>
Subject: Re: [PATCH v4 1/3] dt-bindings: hwmon: fan: Add fan binding to schema



On 24-10-2022 09:48 pm, Rob Herring wrote:
> So if we unload and reload the driver module, it should go back to the
> default?
This is RPM to be set during probe if desired.
> 
> I think it is really, 'target RPM if not already configured' which could
> be keep the setting from a register (e.g. what the bootloader set) or
> perhaps you already have temperature information to use...
Yes. missed it. It should be target-rpm will correct this. in next version.
> 
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +  pwm-frequency:
>> +    description:
>> +      PWM frequency for fan in Hertz(Hz).
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +
>> +  pwm-polarity-inverse:
>> +    description:
>> +      Inverse PWM polarity for fan.
>> +    type: boolean
> As I said before, the PWM binding handles these 2 settings. Use it. Yes,
> it's a bit of an overkill when the child is the consumer of the parent.
> Until some 'clever' h/w engineer decides to use one of the PWMs for
> something else like a backlight.
I would like you to consider this as something recommended by fan 
datasheet for the given fan instance.
This info can be used by fan controller driver to configure PWM 
source/provider accordingly.

If you still feel that may not make sense then I'll remove this property.


Thanks,
Naresh