linux-kernel - Re: [PATCH v1 2/2] iio: temperature: add support for MCP998X

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Message-ID: <303fbf2f6c64241966009be59f68c1d2f8cdc786.camel@microchip.com>
Date: Mon, 28 Apr 2025 12:57:05 +0000
From: <Victor.Duicu@...rochip.com>
To: <jic23@...nel.org>
CC: <Marius.Cristea@...rochip.com>, <andy@...nel.org>,
	<dlechner@...libre.com>, <linux-iio@...r.kernel.org>, <nuno.sa@...log.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/2] iio: temperature: add support for MCP998X

On Fri, 2025-04-18 at 19:07 +0100, Jonathan Cameron wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
> 
> On Tue, 15 Apr 2025 16:26:23 +0300
> <victor.duicu@...rochip.com> wrote:
> 
> > From: Victor Duicu <victor.duicu@...rochip.com>
> > 
> > This is the driver for Microchip MCP998X/33 and MCP998XD/33D
> > Multichannel Automotive Monitor Family.
> > 
> > Signed-off-by: Victor Duicu <victor.duicu@...rochip.com>
> 

Hi Jonathan,

> Hi Victor,
> 
> Various comments inline,
> 
> Thanks,
> 
> Jonathan
> 
> > ---
> >  .../testing/sysfs-bus-iio-temperature-mcp9982 |  17 +
> >  MAINTAINERS                                   |   7 +
> >  drivers/iio/temperature/Kconfig               |  10 +
> >  drivers/iio/temperature/Makefile              |   1 +
> >  drivers/iio/temperature/mcp9982.c             | 794
> > ++++++++++++++++++
> >  5 files changed, 829 insertions(+)
> >  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-
> > temperature-mcp9982
> >  create mode 100644 drivers/iio/temperature/mcp9982.c
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-bus-iio-temperature-
> > mcp9982 b/Documentation/ABI/testing/sysfs-bus-iio-temperature-
> > mcp9982
> > new file mode 100644
> > index 000000000000..de3360fb05be
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-bus-iio-temperature-mcp9982
> > @@ -0,0 +1,17 @@
> > +What:               
> > /sys/bus/iio/devices/iio:deviceX/running_average_window
> 
> As later in review, I think we can control this via the low pass
> filter 3dB point
> and use standard ABI.
> 
> 
> > 
...

> Hmm.  A running average is a low pass filter.  Can we control this
> instead via
> standard ABI and the 3dB point?  Take a look at the filter ABI in
> Documentation/ABI/testing/sysfs-bus-iio
> 
> Custom ABI is rarely used in real cases because the tools tend not to
> know about it
> so we avoid it if we possibly can.
> 
> > +
> > 


The moving average filter is used to smooth the temperature spikes.
The user should be able to set the size of the window to
a few values: 1(disable the filter), 4 and 8.
The user does not have access to the frequency properties.

Best Regards,
Victor
>