Re: [PATCH v6 6/6] iio: dac: ad5504: support scale via output-range-microvolt property

On 8/22/26 3:56 AM, Taha Ed-Dafili wrote:
> The AD5504 output range is set by the R_SEL pin, not the VCC supply.
> Add support for 'output-range-microvolt' to set vref_mv directly from
> firmware. Use device_property_present() to distinguish absent from
> malformed property rather than relying on the ambiguous -EINVAL from
> device_property_read_u32_array(). Fall back to the vcc regulator
> voltage for old DTs that predate this property.
> 
> Signed-off-by: Taha Ed-Dafili <[email protected]>
> ---
>  drivers/iio/dac/ad5504.c | 31 +++++++++++++++++++++++++------
>  1 file changed, 25 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5504.c b/drivers/iio/dac/ad5504.c
> index 74679feea385..d0a3dd4b000d 100644
> --- a/drivers/iio/dac/ad5504.c
> +++ b/drivers/iio/dac/ad5504.c
> @@ -300,6 +300,7 @@ static int ad5504_probe(struct spi_device *spi)
>  	struct device *dev = &spi->dev;
>  	struct iio_dev *indio_dev;
>  	struct ad5504_state *st;
> +	u32 range[2];
>  	int ret;
>  
>  	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> @@ -315,12 +316,30 @@ static int ad5504_probe(struct spi_device *spi)
>  	if (is_acpi_device_node(dev_fwnode(dev))) {
>  		st->vref_mv = AD5504_VREF_ACPI_DEFAULT_mV;
>  	} else {
> -		ret = devm_regulator_get_enable_read_voltage(dev, "vcc");
> -		if (ret < 0)
> -			return dev_err_probe(dev, ret,
> -					     "Failed to get vcc regulator\n");
> -
> -		st->vref_mv = ret / 1000;
> +		if (device_property_present(dev, "output-range-microvolt")) {
> +			ret = device_property_read_u32_array(dev, "output-range-microvolt",
> +							     range, ARRAY_SIZE(range));
> +			if (ret)
> +				return dev_err_probe(dev, ret,
> +							"Error parsing output-range-microvolt\n");
> +
> +			if (range[0] != 0 || (range[1] != 30 * MICRO && range[1] != 60 * MICRO))
> +				return dev_err_probe(dev, -EINVAL,
> +					"Invalid output-range-microvolt\n");
> +
> +			st->vref_mv = range[1] / (MICRO / MILLI);
> +
> +			ret = devm_regulator_get_enable(dev, "vcc");
> +			if (ret < 0)
> +				return dev_err_probe(dev, ret, "Failed to enable vcc regulator\n");

We should probably handle range-sel-gpios here. Otherwise, if a new DT tries
to use it, it will end up falling back to this old wrong behavior.

		} else if (device_property_present("range-sel-gpios")) {
			
Either return an error here that it is not supported. Or implement it by
making IIO_CHAN_INFO_SCALE writable.

> +		} else {
> +			/* Backward compat: old DTs without output-range-microvolt */
> +			ret = devm_regulator_get_enable_read_voltage(dev, "vcc");
> +			if (ret < 0)
> +				return dev_err_probe(dev, ret, "Failed to get vcc regulator\n");
> +
> +			st->vref_mv = ret / (MICRO / MILLI);
> +		}
>  	}
>  
>  	st->spi = spi;