Re: [PATCH v2 3/3] Documentation: ABI: IIO: Drop AD4130 specific filter_type_available options

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 7 Jan 2025 11:53:44 -0600
David Lechner <dlechner@baylibre.com> wrote:

> On 1/7/25 9:13 AM, Marcelo Schmitt wrote:
> > The only driver exporting filter_type_available attribute is ad7779 and it
> > only supports sinc3 and sinc5 filters. Remove options that are not
> > presented through filter_type_available attribute.
> > 
> > Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
> > ---
> > Maybe this is not worth it (or desirable?) since the options may come back in
> > the future if new drivers happen to need them.  
> 
> I would be tempted to add filter_type{,_available} attributes to the ad4130
> driver that mirrors the existing filter_mode{,_available} attributes. We can't
> remove filter_mode since that would break things, but having filter_type in
> addition to that would mean than userspace tools could standardize on
> filter_type and not have to make a special exception for the different naming
> on ad4130.
> 
> Then we wouldn't need to delete the extra items here and we wouldn't have to
> repeat the docs for sysfs-bus-iio-adc-ad4130. Those docs can just have the
> deprecation paragraph and mention that it returns values identical to the
> filter_type attributes for backwards compatibility.

Good idea.  Given we always allow any attribute to change any other, having
duplicates for ABI backwards compatibility is fine.

Thanks,

Jonathan