Re: [PATCH v2 2/2] iio: temperature: Add STS30 temperature sensor driver

[Guenter Roeck]

On 7/6/26 08:53, Jonathan Cameron wrote:
> On Sat, 4 Jul 2026 20:57:17 -0500
> Maxwell Doose <m32285159@xxxxxxxxx> wrote:
>
> > On Sun, 5 Jul 2026 00:00:53 +0100
> > Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> >
> > > On Sat, 4 Jul 2026 14:45:03 -0500
> > > Maxwell Doose <m32285159@xxxxxxxxx> wrote:
> > >    
> > > > Hi Jonathan,
> > > >
> > > > On Fri, 3 Jul 2026 01:05:32 +0100
> > > > Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> > > >      
> > > > > On Sat, 20 Jun 2026 19:46:24 -0500
> > > > > Maxwell Doose <m32285159@xxxxxxxxx> wrote:
> > > > >        
> > > > > > Add a driver for the Sensirion STS30 family of temperature sensor
> > > > > > drivers over I2C. The STS30 family of sensors includes the STS30, STS31,
> > > > > > and STS35, all of which are supported by this driver, since they all
> > > > > > share the same commands, etc. and only differ in accuracy and tolerance.
> > > > > >
> > > > > > The driver currently supports single-shot non-clock stretched readings,
> > > > > > by using a specified delay based on the repeatability/delay specified
> > > > > > by the user. The repeatability/delay can be changed at any time through
> > > > > > sysfs.
> > > > > >
> > > > > > Additionally add Kconfig and Makefile entries for the driver as well as
> > > > > > a MAINTAINERS entry.
> > > > > >
> > > > > > Signed-off-by: Maxwell Doose <m32285159@xxxxxxxxx>
> > > > >
> > > > > Big question first.  Why IIO? These are fairly basic temperature sensors
> > > > > which typically means hwmon is more appropriate.  What does it need
> > > > > that hwmon doesn't provide?
> > > > >        
> > > >
> > > > The datasheet says that the STS30 supports continuous reads which means
> > > > that we can read it into a triggered buffer (which hwmon doesn't
> > > > support) and at some point I'd like to implement that.
> > >
> > > Hmm. For a temperature chip that is often more about the monitors running
> > > continuously than the ability to gather signals fast.  Temperature changes
> > > tend to be fairly slow when it's a physical sensor - gets less obvious when
> > > infrared remote sensors are involved.
> > >
> > > Even more relevant - there is an existing driver I think.
> > > See drivers/hwmon/sht3x.c which supports things under the wildcard sts3x as well.
> > > Check if that covers this part.
> > >    
> >
> > I think the last time I checked the sts30 series wasn't listed in the
> > dt-bindings but it may have changed since then. Oh well. I'll still go
> > check it out. If it's (very very) similar I would probably consider
> > dropping this one, otherwise I'll improve this one and resubmit once I
> > get the hardware.
>
>
> Unless that other driver is for a very different part, then it is a non
> starter to have a driver in IIO.  Perhaps there are features missing in
> the hwmon driver though. +CC Guenter and hwmon so they are aware of
> this discussion.

I have no idea what might be missing, or why the existing hwmon driver
would not be sufficient. Lack of explicit devicetree support, as
suggested above ? That would require a few lines of code and an odd
reason to duplicate the driver in the iio subsystem. Triggered buffer ?
That makes sense for high speed ADCs, but not for low speed sensors
like this one.

Guenter