Re: [PATCH v3] iio: dac: max5522: simplify probe with devm_regulator_get_enable_read_voltage()

[Jonathan Cameron]

On Mon, 16 Feb 2026 15:17:05 +0200
Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx> wrote:

> Simplify probe by using devm_regulator_get_enable_read_voltage() to
> get, enable and read the regulator voltage in a single call, caching
> the value at probe time.
> 
> The reference voltage for this DAC is a fixed hardware configuration
> that is not expected to change at runtime, so reading it once during
> probe and caching the millivolt value is sufficient.
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx>
Applied.  Thanks,

Jonathan

> ---
> Changes in v3:
>  - change vref_mV type from unsigned short to int to avoid potential
>    precision loss
>  - update commit message to clarify why caching voltage at probe is
>    sufficient
> 
>  drivers/iio/dac/max5522.c | 22 +++++++---------------
>  1 file changed, 7 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/iio/dac/max5522.c b/drivers/iio/dac/max5522.c
> index 1b8fe6b8d26e..b52a9cc1da79 100644
> --- a/drivers/iio/dac/max5522.c
> +++ b/drivers/iio/dac/max5522.c
> @@ -14,6 +14,7 @@
>  #include <linux/regulator/consumer.h>
>  #include <linux/slab.h>
>  #include <linux/spi/spi.h>
> +#include <linux/units.h>
>  
>  #include <linux/iio/iio.h>
>  
> @@ -34,7 +35,7 @@ struct max5522_state {
>  	struct regmap *regmap;
>  	const struct max5522_chip_info *chip_info;
>  	unsigned short dac_cache[2];
> -	struct regulator *vrefin_reg;
> +	int vref_mV;
>  };
>  
>  #define MAX5522_CHANNEL(chan) {	\
> @@ -79,17 +80,13 @@ static int max5522_read_raw(struct iio_dev *indio_dev,
>  			    int *val, int *val2, long info)
>  {
>  	struct max5522_state *state = iio_priv(indio_dev);
> -	int ret;
>  
>  	switch (info) {
>  	case IIO_CHAN_INFO_RAW:
>  		*val = state->dac_cache[chan->channel];
>  		return IIO_VAL_INT;
>  	case IIO_CHAN_INFO_SCALE:
> -		ret = regulator_get_voltage(state->vrefin_reg);
> -		if (ret < 0)
> -			return -EINVAL;
> -		*val = ret / 1000;
> +		*val = state->vref_mV;
>  		*val2 = 10;
>  		return IIO_VAL_FRACTIONAL_LOG2;
>  	default:
> @@ -147,16 +144,11 @@ static int max5522_spi_probe(struct spi_device *spi)
>  	if (!state->chip_info)
>  		return -EINVAL;
>  
> -	state->vrefin_reg = devm_regulator_get(&spi->dev, "vrefin");
> -	if (IS_ERR(state->vrefin_reg))
> -		return dev_err_probe(&spi->dev, PTR_ERR(state->vrefin_reg),
> -				     "Vrefin regulator not specified\n");
> -
> -	ret = regulator_enable(state->vrefin_reg);
> -	if (ret) {
> +	ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vrefin");
> +	if (ret < 0)
>  		return dev_err_probe(&spi->dev, ret,
> -				     "Failed to enable vref regulators\n");
> -	}
> +				     "Failed to get vrefin regulator\n");
> +	state->vref_mV = ret / (MICRO / MILLI);
>  
>  	state->regmap = devm_regmap_init_spi(spi, &max5522_regmap_config);
>