Re: [PATCH v2 07/10] hwmon: (tmp421) really disable channels

[Guenter Roeck <linux@roeck-us.net>]

On Fri, Sep 24, 2021 at 11:42:40AM +0200, Krzysztof Adamski wrote:
> Recent patch added possibility to disable selected channels. That would
> only make sure that the ENODATA is returned for those channels but would
> not configure the actual hardware.
> 
> With this patch, the config register is written to make sure the
> channels are disabled also at hardware level.
> 
> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
> ---
>  drivers/hwmon/tmp421.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
> index 0fa4c02f5808..4934ce13afb4 100644
> --- a/drivers/hwmon/tmp421.c
> +++ b/drivers/hwmon/tmp421.c
> @@ -33,6 +33,9 @@ enum chips { tmp421, tmp422, tmp423, tmp441, tmp442 };
>  /* The TMP421 registers */
>  #define TMP421_STATUS_REG			0x08
>  #define TMP421_CONFIG_REG_1			0x09
> +#define TMP421_CONFIG_REG_2			0x0A
> +#define TMP421_CONFIG_REG_REN(x)		(BIT(3 + (x)))
> +#define TMP421_CONFIG_REG_REN_MASK		(BIT(3)|BIT(4)|BIT(5)|BIT(6))

GENMASK() would probably be better here.

>  #define TMP421_CONVERSION_RATE_REG		0x0B
>  #define TMP421_N_FACTOR_REG_1			0x21
>  #define TMP421_MANUFACTURER_ID_REG		0xFE
> @@ -155,6 +158,33 @@ static struct tmp421_data *tmp421_update_device(struct device *dev)
>  	return data;
>  }
>  
> +static int tmp421_enable_channels(struct tmp421_data *data)
> +{
> +	int err;
> +	struct i2c_client *client = data->client;
> +	struct device *dev = &client->dev;
> +	int cfg = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_2);
> +	int i;
> +
> +	if (cfg < 0) {
> +		dev_err(dev,
> +			"error reading register, can't disable channels\n");

Unnecessary line break

> +		return err;

		return cfg;

> +	}
> +
> +	cfg &= ~TMP421_CONFIG_REG_REN_MASK;
> +	for (i = 0; i < data->channels; i++)
> +		if (data->channel[i].enabled)
> +			cfg |= TMP421_CONFIG_REG_REN(i);
> +
> +	err = i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_2, cfg);
> +	if (err < 0)
> +		dev_err(dev,
> +			"error writing register, can't disable channels\n");

Unnecessary line break

> +
> +	return err;
> +}
> +
>  static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
>  		       u32 attr, int channel, long *val)
>  {
> @@ -395,6 +425,10 @@ static int tmp421_probe(struct i2c_client *client)
>  	if (err)
>  		return err;
>  
> +	err = tmp421_enable_channels(data);
> +	if (err)
> +		return err;

This should really be called from tmp421_init_client(). After all, that is what
the function is for.

> +
>  	data->chip.ops = &tmp421_ops;
>  	data->chip.info = data->info;
>