Re: [PATCH 2/2] iio: temperature: ltc2983: Add support for ADT7604

[Jonathan Cameron]

On Fri, 8 May 2026 17:13:14 +0100
Nuno Sá <noname.nuno@xxxxxxxxx> wrote:

> On Fri, May 08, 2026 at 02:48:39PM +0000, Stan, Liviu wrote:
> > On Fri, May 08, 2026 Nuno Sá wrote:  
> > > > On Fri, 8 May 2026 Jonathan Cameron wrote:  
> > > > > > Will defer this to Jonathan but if we can have a real of the coverage
> > > > > > given the temperature, I guess this is ok. Given that I think we don't have
> > > > > > a better channel (unless we add one?) for this. Or just extended_info...
> > > > > >  
> > > > >
> > > > > I have no idea what coverage percentage means in this case.
> > > > > Can you provide some more details or a reference?  Google isn't giving me
> > > > > anything useful.  
> > > >
> > > > A leak detector is a sensor like the raindrop detection modules, whose
> > > > resistance decreases as more of its surface is contacted by liquid. In this case,
> > > > for example, if half of the sensor's surface is in contact with a liquid, the
> > > > ADT7604 should, with an appropiate user-provided resistance-vs-coverage
> > > > table, report 50% coverage in the IIO channel.  
> > > 
> > > And, AFAIU, depending on the coverage the resistance changes and that's
> > > how we get into the indirect temperature variations?  
> > 
> > If I understand your comment correctly, you're implying that there are indirect
> > temperature variations caused by resistance changes, and that's what the chip is
> > measuring? The chip does not measure any actual temperature for this sensor
> > type, the value in the temperature result register bank is solely a result of the 
> > chip's interpolation of the user-defined custom table.
> >   
> 
> I meant that's what the table is trying to accomplish? That's why I kind
> of put it as "indirect". My understanding was the chip does not measure
> any temperature as well.

Ok. So what are our options here?  Present it as simple resistance and leave
userspace to figure it out or add a new channel type? To me feels like new
channel type makes sense.

Jonathan


> 
> - Nuno Sá
> 
> > Liviu