Re: [PATCH 14/22] iio: dac: ad5686: add support for missing power supplies

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 22 Apr 2026 15:45:48 +0100
Rodrigo Alencar via B4 Relay <devnull+rodrigo.alencar.analog.com@kernel.org> wrote:

> From: Rodrigo Alencar <rodrigo.alencar@analog.com>
> 
> Get optional regulators for vdd, vlogic and vref input power pins. vdd is
> the input power supply, while vlogic powers the digital side. vref is
> replacing vcc, which is being deprecated, but still supported. The value
> of vref_mv is checked so that a device without internal voltage reference
> cannot proceed without an explicit supply. Error report uses
> dev_err_probe(), which helps debugging an init issue.
> 
> Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
> ---
>  drivers/iio/dac/ad5686.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
> index 07a944311f0e..4989404a7b6e 100644
> --- a/drivers/iio/dac/ad5686.c
> +++ b/drivers/iio/dac/ad5686.c
> @@ -7,6 +7,7 @@
>  
>  #include <linux/array_size.h>
>  #include <linux/bitfield.h>
> +#include <linux/dev_printk.h>
>  #include <linux/err.h>
>  #include <linux/export.h>
>  #include <linux/module.h>
> @@ -471,13 +472,27 @@ int ad5686_probe(struct device *dev,
>  	st->read = read;
>  	st->chip_info = chip_info;
>  
> -	ret = devm_regulator_get_enable_read_voltage(dev, "vcc");
> +	ret = devm_regulator_get_enable_optional(dev, "vdd");
> +	if (ret && ret != -ENODEV)
> +		return dev_err_probe(dev, ret, "failed to enable vdd supply\n");
vdd is very rarely optional.  Can we not rely on the stub regulator
that will be provided if there isn't one in DT?
> +
> +	ret = devm_regulator_get_enable_optional(dev, "vlogic");
Also doesn't sound very optional.

> +	if (ret && ret != -ENODEV)
> +		return dev_err_probe(dev, ret, "failed to enable vlogic supply\n");
> +
> +	ret = devm_regulator_get_enable_read_voltage(dev, "vref");
> +	if (ret == -ENODEV) /* vcc-supply is deprecated, but supported still */
> +		ret = devm_regulator_get_enable_read_voltage(dev, "vcc");
>  	if (ret < 0 && ret != -ENODEV)
> -		return ret;
> +		return dev_err_probe(dev, ret, "failed to read vref voltage\n");
>  
>  	st->use_internal_vref = ret == -ENODEV;
>  	st->vref_mv = st->use_internal_vref ? st->chip_info->int_vref_mv : ret / 1000;
>  
> +	if (!st->vref_mv)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "invalid or not provided vref voltage\n");
> +
>  	/* Set all the power down mode for all channels to 1K pulldown */
>  	st->pwr_down_mode = ~0U;
>  	st->pwr_down_mask = ~0U;
>