Re: [PATCH v7 7/7] iio: dac: ad5686: add gain control support

On 7/10/26 6:20 AM, Rodrigo Alencar via B4 Relay wrote:
> From: Rodrigo Alencar <[email protected]>
> 
> Most of the supported devices rely on a GAIN pin to control a 2x
> multiplier applied to the output voltage. Other devices, e.g. the
> single-channel ones, provides a gain control through a bit field in
> the control register. Some designs might have the GAIN pin hardwired
> to VDD/VLOGIC or GND, which would have no "gain-gpios" device property,
> being able to set "adi,range-double" if it is hardwired to VDD. The
> vref_mv field is moved down in the struct ad5686_state, so that the
> overall size increase is reduced.
> 

...

> @@ -217,6 +229,82 @@ static int ad5686_write_raw(struct iio_dev *indio_dev,
>  
>  		return ad5686_write(st, AD5686_CMD_WRITE_INPUT_N_UPDATE_N,
>  				    chan->address, val << chan->scan_type.shift);
> +	case IIO_CHAN_INFO_SCALE:
> +		if (val == st->scale_avail[0] && val2 == st->scale_avail[1])
> +			double_scale = false;
> +		else if (val == st->scale_avail[2] && val2 == st->scale_avail[3])
> +			double_scale = true;
> +		else
> +			return -EINVAL;
> +
> +		if (st->double_scale == double_scale)
> +			return 0; /* no change */
> +
> +		if (st->chip_info->regmap_type == AD5686_REGMAP && !st->gain_gpio)

This condition is used a couple of times. It could be nice to just add a
st->pin_strapped_gain field to make it self-documenting and use that instead.

> +			return -EINVAL; /* GAIN pin is board-strapped */
> +
> +		st->double_scale = double_scale;
> +		switch (st->chip_info->regmap_type) {
> +		case AD5310_REGMAP:
> +			ret = ad5310_control_sync(st);
> +			break;
> +		case AD5683_REGMAP:
> +			ret = ad5683_control_sync(st);
> +			break;
> +		case AD5686_REGMAP:
> +			ret = gpiod_set_value_cansleep(st->gain_gpio,
> +						       st->double_scale ? 1 : 0);
> +			break;
> +		default:
> +			ret = -EINVAL;
> +		}
> +		if (ret)
> +			st->double_scale = !double_scale; /* revert on failure */
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +