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Date: Mon, 11 Mar 2024 11:34:38 -0600
From: Rob Herring <robh@kernel.org>
To: Chanh Nguyen <chanh@os.amperecomputing.com>
Cc: Jean Delvare <jdelvare@suse.com>, Guenter Roeck <linux@roeck-us.net>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Justin Ledford <justinledford@google.com>,
	devicetree@vger.kernel.org, linux-hwmon@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	OpenBMC Maillist <openbmc@lists.ozlabs.org>,
	Open Source Submission <patches@amperecomputing.com>,
	Phong Vo <phong@os.amperecomputing.com>,
	Thang Nguyen <thang@os.amperecomputing.com>,
	Quan Nguyen <quan@os.amperecomputing.com>
Subject: Re: [PATCH 3/3] dt-bindings: hwmon: max31790: Add
 pwmout-pin-as-tach-input property
Message-ID: <20240311173438.GA1451467-robh@kernel.org>
References: <20240311111347.23067-1-chanh@os.amperecomputing.com>
 <20240311111347.23067-4-chanh@os.amperecomputing.com>
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In-Reply-To: <20240311111347.23067-4-chanh@os.amperecomputing.com>

On Mon, Mar 11, 2024 at 06:13:47PM +0700, Chanh Nguyen wrote:
> Add pwmout-pin-as-tach-input property.
> 
> Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
> ---
>  Documentation/devicetree/bindings/hwmon/max31790.yaml | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/max31790.yaml b/Documentation/devicetree/bindings/hwmon/max31790.yaml
> index 5a93e6bdebda..447cac17053a 100644
> --- a/Documentation/devicetree/bindings/hwmon/max31790.yaml
> +++ b/Documentation/devicetree/bindings/hwmon/max31790.yaml
> @@ -25,6 +25,16 @@ properties:
>    reg:
>      maxItems: 1
>  
> +  pwmout-pin-as-tach-input:
> +    description: |
> +      An array of six integers responds to six PWM channels for
> +      configuring the pwm to tach mode.
> +      When set to 0, the associated PWMOUT produces a PWM waveform for
> +      control of fan speed. When set to 1, PWMOUT becomes a TACH input
> +    $ref: /schemas/types.yaml#/definitions/uint8-array
> +    maxItems: 6
> +    minItems: 6

Seems incomplete. For example, fan tachs have different number of 
pulses per revolution, don't you need to know that too? 

There's a common fan binding now (or pending). You should use that and 
this property won't be needed.

Rob