linux-kernel - Re: [PATCH] hwmon: (tmp108) Add basic regulator support

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Message-ID: <fcf06424-c014-4e87-9ac5-ced1ea679fdd@roeck-us.net>
Date: Sat, 30 Nov 2024 09:58:17 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Stanislav Jakubek <stano.jakubek@...il.com>,
 Jean Delvare <jdelvare@...e.com>
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
 Frank Li <Frank.Li@....com>
Subject: Re: [PATCH] hwmon: (tmp108) Add basic regulator support

On 11/26/24 00:40, Stanislav Jakubek wrote:
> TMP108/P3T1085 are powered by the V+/VCC regulator, add support for it.
> 
> Signed-off-by: Stanislav Jakubek <stano.jakubek@...il.com>
> ---
>   drivers/hwmon/tmp108.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/hwmon/tmp108.c b/drivers/hwmon/tmp108.c
> index 1f36af2cd2d9..85e4466259a3 100644
> --- a/drivers/hwmon/tmp108.c
> +++ b/drivers/hwmon/tmp108.c
> @@ -17,6 +17,7 @@
>   #include <linux/init.h>
>   #include <linux/jiffies.h>
>   #include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
>   #include <linux/slab.h>
>   
>   #define	DRIVER_NAME "tmp108"
> @@ -331,6 +332,10 @@ static int tmp108_common_probe(struct device *dev, struct regmap *regmap, char *
>   	u32 config;
>   	int err;
>   
> +	err = devm_regulator_get_enable(dev, "vcc");
> +	if (err)
> +		return dev_err_probe(dev, err, "Failed to enable regulator\n");
> +

Problem with this is that existing devicetree bindings do not provide
a reference to the regulator. Those would now fail to instantiate,
which would be unacceptable. I think you'll need something like

	err = devm_regulator_get_enable_optional(dev, "vcc");
	if (err && err != -ENODEV)
		return dev_err_probe(dev, err, "Failed to enable regulator\n");

Even though the regulator is now mandatory, existing devicetree bindings
don't know that.

Guenter