On Tue, Jun 02, 2026 at 05:33:59PM +0100, Rodrigo Alencar via B4 Relay wrote:
>
> 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 still be fine for this patch, that allows
> the scale property to be configurable with two available options.
...
> + case IIO_CHAN_INFO_SCALE:
> + if (val == st->scale_avail[0] && val2 == st->scale_avail[1])
> + st->double_scale = false;
> + else if (val == st->scale_avail[2] && val2 ==
> st->scale_avail[3])
> + st->double_scale = true;
> + else
> + return -EINVAL;
> +
> + switch (st->chip_info->regmap_type) {
> + case AD5310_REGMAP:
> + return ad5310_control_sync(st);
> + case AD5683_REGMAP:
> + return ad5683_control_sync(st);
> + case AD5686_REGMAP:
> + /*
> + * even if the gain pin is hardwired on the board, the
Even
> + * user is able to control the scale such that it
> + * matches the actual gain setting.
> + */
> + gpiod_set_value_cansleep(st->gain_gpio,
> + st->double_scale ? 1 : 0);
> + return 0;
> + default:
> + return -EINVAL;
> + }
...
> @@ -138,9 +143,12 @@ struct ad5686_state {
Have you run `pahole`? It seems to me that those bools can be combined with
vref_mv to reduce 4 bytes gap.
> const struct ad5686_chip_info *chip_info;
> const struct ad5686_bus_ops *ops;
> struct gpio_desc *ldac_gpio;
> + struct gpio_desc *gain_gpio;
> unsigned short vref_mv;
> unsigned int pwr_down_mask;
> unsigned int pwr_down_mode;
> + int scale_avail[4];
> + bool double_scale;
> bool use_internal_vref;
> struct mutex lock;
> void *bus_data;
--
With Best Regards,
Andy Shevchenko
