Re: [PATCH v2 05/16] Documentation: ABI: add wideband filter type to sysfs-bus-iio

[Jonathan Cameron]

On Mon, 27 Jan 2025 19:32:45 -0600
David Lechner <dlechner@xxxxxxxxxxxx> wrote:

> On 1/27/25 9:12 AM, Jonathan Santos wrote:
> > The Wideband Low Ripple filter is used for AD7768-1 Driver.
> > Document wideband filter option into filter_type_available
> > attribute.
> > 
> > Signed-off-by: Jonathan Santos <Jonathan.Santos@xxxxxxxxxx>
> > ---
> > v2 Changes:
> > * Removed FIR mentions.
> > ---
> >  Documentation/ABI/testing/sysfs-bus-iio | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> > index f83bd6829285..9b879e7732cd 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-iio
> > +++ b/Documentation/ABI/testing/sysfs-bus-iio
> > @@ -2291,6 +2291,8 @@ Description:
> >  		* "sinc3+pf2" - Sinc3 + device specific Post Filter 2.
> >  		* "sinc3+pf3" - Sinc3 + device specific Post Filter 3.
> >  		* "sinc3+pf4" - Sinc3 + device specific Post Filter 4.
> > +		* "wideband" - filter with wideband low ripple passband
> > +		  and sharp transition band.
> >  
> >  What:		/sys/.../events/in_proximity_thresh_either_runningperiod
> >  KernelVersion:	6.6  
> 
> I'm a bit shy to make any more suggestions on this one since my previous
> suggestions were clearly not the "right way". :-)
> 
> But, the key takeaway I got from the discussion on v1 is that this describes the
> _shape_ of the filter. To me, "wideband" describes the size but not the shape.
> Would rectangular be the correct shape?
> 
It's tricky.  The filter definition is really vague!  No filter is ever rectangular.
Also, I've just noticed. This one is fully programable. It could be anything!
I kind of hope no one cares about that feature as it looks really tricky to support.


Wideband normally means 'flattish to a wide range of frequencies'.  Not sure
how best to convey that.