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Sender: Guenter Roeck <groeck7@gmail.com>
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Date:   Mon, 7 Aug 2023 20:54:10 -0700
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To:     Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>,
        Jean Delvare <jdelvare@suse.com>
Cc:     linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
        Mathew McBride <matt@traverse.com.au>
References: <20230808013157.80913-1-mark.tomlinson@alliedtelesis.co.nz>
 <20230808013157.80913-2-mark.tomlinson@alliedtelesis.co.nz>
From:   Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH 2/2] dt-bindings: hwmon: add EMC181x
In-Reply-To: <20230808013157.80913-2-mark.tomlinson@alliedtelesis.co.nz>
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On 8/7/23 18:31, Mark Tomlinson wrote:
> The EMC181x range are I2C temperature sensors with a varying number of
> sensors in each device. Each has one internal sensor, and one to four
> external sensor diodes.
> 
> The default range is from 0°C to +127°C, but can be extended to -64°C to
> +191°C.
> 
> Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
> ---
>   .../bindings/hwmon/microchip,emc181x.yaml     | 45 +++++++++++++++++++
>   1 file changed, 45 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/hwmon/microchip,emc181x.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/microchip,emc181x.yaml b/Documentation/devicetree/bindings/hwmon/microchip,emc181x.yaml
> new file mode 100644
> index 000000000000..5967f98ad7ba
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/microchip,emc181x.yaml
> @@ -0,0 +1,45 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +
> +$id: http://devicetree.org/schemas/hwmon/microchip,emc181x.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Microchip EMC1812/EMC1813/EMC1814/EMC1815/EMC1833 temperature sensors
> +
> +maintainers:
> +  - Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - microchip,emc1812
> +      - microchip,emc1813
> +      - microchip,emc1814
> +      - microchip,emc1815
> +      - microchip,emc1833
> +
> +  reg:
> +    maxItems: 1
> +
> +  emc181x,extended-range:
> +    description: Allow for reading of extended temperature range (-64-192C)
> +
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +

The chip has various other configuration options. I would have expected to see
at least beta compensation, ideality factor, resistance error correction,
and anti-parallel diode operation.

Yes, I understand you probably don't plan to implement those in the driver,
but the devicetree property description should at least try to be complete.

Guenter

> +examples:
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        temperature-sensor@7c {
> +            compatible = "microchip,emc1812";
> +            reg = <0x7c>;
> +        };
> +    };