Re: [PATCH v3 0/4] iio: adc: ad9467: Support alternative backends

Tomas Melin
2026-01-14T15:32:08Z

Hi Nuno,

On 14/01/2026 15:32, Nuno Sá wrote:
> On Wed, 2026-01-14 at 10:45 +0000, Tomas Melin wrote:
>> To facilitate backends with different set of features, add support
>> for defining capabilites provided by the backend. These capabilites
>> typically extend beyond a single operation and are therefore not
>> directly linked to if a single function call is implemented or not.
>> Furthermore, the capabilites determine if a certain set of operations
>> should be attempted, or skipped by the frontend. This way
>> the frontend driver can work with a minimalistic set of features and
>> still have the device in fully functional state.
>>
>> Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
>> ---
>
> Hi Tomas,
>
>> Changes in v3:
>> - Reduce set of capabilities to only include calibration. The other
>>   ones propsed in V2 can be seen as subset of calibration, or single
>>   operation failing with opnotsupported
>
> As stated in my patch comment. Using opnotsupported for buffers defeats
> the CAPS idea.
Please check my other reply, to me adding cap for a 1:1 mapping of a
operation seems like duplicating the information. But of course, this
can be viewed from different angles and it is also possible to look at
it like that.

>
>
> But more importantly, how are your usecase supposed to work with this
> series? I'm not seeing any new backend being added as part of the series.
> Point is, if we are adding all of this, I would expect your usecase to
> have fully upstream support. If I'm not missing nothing, we would at least
> need a dummy backend providing stubs for enable()/disable()
My usecase adds simplistic backend support and registers to the
framework via an related driver. So that use case works with that
approach. I think it is better to assume there is always some entity
that can take on the role of being backend, rather than adding a dummy
backend. Adding the capabilities are defining role here, as having that
allows for customer integrations with backends that differ but are of no
interest for the mainline.

Thanks,
Tomas

>
> - Nuno Sá