Re: [PATCH] iio: adc: ti-ads8688: use read_avail for available attributes

[Andy Shevchenko]

On Mon, Mar 23, 2026 at 09:56:33PM +0000, Gabriel Rondon wrote:
> Convert the in_voltage_scale_available and in_voltage_offset_available
> attributes from legacy IIO_DEVICE_ATTR with custom show functions to the
> IIO framework's read_avail callback. This uses the framework's built-in
> support for _available attributes, removing the need for manual sysfs
> formatting.
> 
> Precompute the available scale values at probe time since they depend on
> the reference voltage which does not change after initialization.

...

> +static const int ads8688_offset_avail[] = {
> +	-(1 << (ADS8688_REALBITS - 1)),

This is fragile code (however it probably won't be exposed IRL)
if ADS8688_REALBITS == 32 this is UB in accordance with C standard.

Also the trick with -BIT(x) is harder to read than simple GENMASK().
If ADS8688_REALBITS == 1, this becomes -1 (all ones), is it correct?

> +	0,

Do not add trailing comma to a terminator.

>  };

...

> static const struct attribute_group ads8688_attribute_group = {

>  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)		\
>  			      | BIT(IIO_CHAN_INFO_SCALE)	\
>  			      | BIT(IIO_CHAN_INFO_OFFSET),	\
> +	.info_mask_shared_by_type_available =			\
> +			      BIT(IIO_CHAN_INFO_SCALE)		\
> +			      | BIT(IIO_CHAN_INFO_OFFSET),	\

This is actually slightly different style to what is put in the above.
Ideally should be unified, but probably matter for another change
(if even needed).

>  	.scan_index = index,					\
>  	.scan_type = {						\
>  		.sign = 'u',					\

>  }

...

> -	int ret;
> +	int ret, i;

Why is 'i' signed?

...


> +	for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++) {

	for (unsigned int i = 0; i < ARRAY_SIZE(st->scale_avail); i++) {

should be good.

> +		st->scale_avail[i][0] = 0;

> +		st->scale_avail[i][1] = ads8688_range_def[i].scale *
> +					st->vref_mv;

I would leave this on a single line (it's only 81 characters).

> +	}

-- 
With Best Regards,
Andy Shevchenko