Re: [PATCH v1 03/15] Documentation: ABI: testing: ad7768-1: Add device specific ABI documentation.

[David Lechner]

On 1/7/25 9:24 AM, Jonathan Santos wrote:
> Add ABI documentation specific to the ad7768-1 device, detailing
> the decimation_rate attribute for better clarity and usability.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@xxxxxxxxxx>
> ---
>  .../ABI/testing/sysfs-bus-iio-adc-ad7768-1          | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-ad7768-1
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-ad7768-1 b/Documentation/ABI/testing/sysfs-bus-iio-adc-ad7768-1
> new file mode 100644
> index 000000000000..065247f07cfb
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-ad7768-1
> @@ -0,0 +1,13 @@
> +What:		/sys/bus/iio/devices/iio:deviceX/decimation_rate_available
> +KernelVersion:
> +Contact:	linux-iio@xxxxxxxxxxxxxxx
> +Description:
> +		Reading returns a range of possible decimation rate values.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/decimation_rate
> +KernelVersion:
> +Contact:	linux-iio@xxxxxxxxxxxxxxx
> +Description:
> +		Sets up the decimation rate for the digital filter. This can
> +		directly impact in the final sampling frequency. Reading returns
> +		the decimation rate. Writing sets the decimation rate.

If this only affects the filter, I would suggest to add `filter_` to the
beginning of the attribute names.

Also, an explanation of how to interpret the numbers would be helpful. It looks
like a unitless number that acts a sort of a multiplier or divider, but that
part isn't so clear to me. 

Or...

Since the decimation rate affects the -3dB point of the filters we could use
the standard IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY instead of introducing
a new attribute.