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Sender: Guenter Roeck <groeck7@gmail.com>
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Date:   Wed, 6 Apr 2022 05:12:18 -0700
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To:     Camel Guo <camel.guo@axis.com>, Jean Delvare <jdelvare@suse.com>,
        Jonathan Corbet <corbet@lwn.net>
Cc:     kernel@axis.com, Camel Guo <camelg@axis.com>,
        linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20220406092901.408861-1-camel.guo@axis.com>
From:   Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH] hwmon: (tmp401) Support extended temperature range
In-Reply-To: <20220406092901.408861-1-camel.guo@axis.com>
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On 4/6/22 02:29, Camel Guo wrote:
> From: Camel Guo <camelg@axis.com>
> 
> This patch only applies to tmp431 and devicetree configuration.
> 
> Signed-off-by: Camel Guo <camelg@axis.com>
> ---
>   Documentation/hwmon/tmp401.rst | 13 +++++++++++++
>   drivers/hwmon/tmp401.c         |  5 +++++
>   2 files changed, 18 insertions(+)
> 
> diff --git a/Documentation/hwmon/tmp401.rst b/Documentation/hwmon/tmp401.rst
> index 3aacf3d3bdf3..d12e9c9ba40f 100644
> --- a/Documentation/hwmon/tmp401.rst
> +++ b/Documentation/hwmon/tmp401.rst
> @@ -78,3 +78,16 @@ some additional features.
>   
>   TMP432 is compatible with TMP401 and TMP431. It supports two external
>   temperature sensors.
> +
> +Device tree
> +-----------
> +TMP431 has support for the device tree parameter "extended-range" which enables
> +the extended range in the chip.
> +

There is no practical reason to limit support for this to TMP431,
nor does the actual code make such a distinction.

> +Example:
> +
> +main-temp@4c {
> +  compatible = "ti,tmp431";
> +  reg = <0x4c>;
> +  extended-range;
> +};

This is not an acceptable way to describe devicetree properties.
You would have to write a bindings document
(Documentation/devicetree/bindings/hwmon/ti,tmp401.yaml)
and describe the property there.

Guenter

> diff --git a/drivers/hwmon/tmp401.c b/drivers/hwmon/tmp401.c
> index b86d9df7105d..6efd2475ffda 100644
> --- a/drivers/hwmon/tmp401.c
> +++ b/drivers/hwmon/tmp401.c
> @@ -557,6 +557,11 @@ static int tmp401_init_client(struct tmp401_data *data)
>   	config_orig = config;
>   	config &= ~TMP401_CONFIG_SHUTDOWN;
>   
> +	if (of_property_read_bool(data->client->dev.of_node, "extended-range")) {
> +		/* Enable extended range */
> +		config |= TMP401_CONFIG_RANGE;
> +	}
> +
>   	data->extended_range = !!(config & TMP401_CONFIG_RANGE);
>   
>   	if (config != config_orig)