linux-kernel - Re: [PATCH v1 1/2] dt-bindings: hwmon: add INA233 binding documents

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Message-ID: <76c39035-06a4-a7db-50e5-517004c0dad9@roeck-us.net>
Date:   Wed, 20 Sep 2023 09:14:59 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Delphine CC Chiu <Delphine_CC_Chiu@...ynn.com>, patrick@...cx.xyz,
        Jean Delvare <jdelvare@...e.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] dt-bindings: hwmon: add INA233 binding documents

On 9/19/23 22:47, Delphine CC Chiu wrote:
> Add INA233 binding documents for Yosemite V4 config.
> 
> Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@...ynn.com>
> ---
>   .../devicetree/bindings/hwmon/ina233.txt      | 27 +++++++++++++++++++
>   MAINTAINERS                                   |  6 +++++
>   2 files changed, 33 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/hwmon/ina233.txt
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/ina233.txt b/Documentation/devicetree/bindings/hwmon/ina233.txt
> new file mode 100644
> index 000000000000..a1067788ec0c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/ina233.txt
> @@ -0,0 +1,27 @@
> +Bindings for the Maxim MAX31790 Intelligent Fan Controller

Not really.

> +==========================================================
> +
> +Reference:
> +
> +https://pdf1.alldatasheet.com/datasheet-pdf/view/930928/TI1/INA233.html
> +
> +The INA233 device is a current, voltage and power monitor with an I2C-, SMBus-,and PMBus-compatible interface
> +that is compliant with digital bus voltages from 1.8 V to 5.0 V.
> +The device monitors and reports values for current, voltage and power.
> +The integrated power accumulator can be used for energy or average power calculations.
> +Programmable calibration value, conversion times and averaging when combined with an internal multiplier
> +enable direct readouts of current in amperes and power in watts.
> +
> +Required properties:
> +- compatible     	: ti,ina233
> +- reg            	: I2C address
> +- resistor-calibration  : MFR_CALIBRATION which will be set into register 0xd4
> +- current-lsb    	: Current_LSB for calibration

The lack of valid ranges is a concern for me, as well as the lack of units.
MFR_CALIBRATION is register 0xd4, so I don't think that "MFR_CALIBRATION
which will be set into register 0xd4" is a really useful description.

Also, the calibration register value is, per datasheet, supposed to be
calculated from current_lsb and Rshunt. Since current_lsb is calculated
from the maximum expected current, the properties should actually be
the maximum expected current and Rshunt.

> +Example:
> +
> +        ina233@45 {
> +                compatible = "ti,ina233";
> +                reg = <0x45>;
> +                resistor-calibration = /bits/ 16 <0x0a00>;
> +                current-lsb= /bits/ 16 <0x0001>;
> +        };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index bf0f54c24f81..48b9a73d259f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10243,6 +10243,12 @@ F:	Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml
>   F:	Documentation/hwmon/ina209.rst
>   F:	drivers/hwmon/ina209.c
>   
> +INA233 HARDWARE MONITOR DRIVER
> +M:     Delphine CC Chiu <Delphine_CC_Chiu@...ynn.com>
> +S:     Odd Fixes
> +F:     Documentation/devicetree/bindings/hwmon/ina233.txt
> +F:     drivers/hwmon/ina233.c
> +
>   INA2XX HARDWARE MONITOR DRIVER
>   M:	Guenter Roeck <linux@...ck-us.net>
>   L:	linux-hwmon@...r.kernel.org