linux-kernel - Re: [PATCH v2 0/2] iio: magnetometer: add support for Infineon TLV493D 3D Magnetic Sensor

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Message-ID: <CAHp75Ve8GOGYLSYgWDncTJOE5_iJqzxQ4BYmvgQ0AO5YYF1K3A@mail.gmail.com>
Date: Sat, 2 Aug 2025 15:17:32 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Dixit Parmar <dixitparmar19@...il.com>, David Lechner <dlechner@...libre.com>, 
	Nuno Sá <nuno.sa@...log.com>, 
	Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, linux-kernel@...r.kernel.org, 
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 0/2] iio: magnetometer: add support for Infineon
 TLV493D 3D Magnetic Sensor

On Sat, Aug 2, 2025 at 1:16 PM Jonathan Cameron <jic23@...nel.org> wrote:
>
> On Sat, 2 Aug 2025 10:53:30 +0200
> Andy Shevchenko <andy.shevchenko@...il.com> wrote:
> > On Sat, Aug 2, 2025 at 8:44 AM Dixit Parmar <dixitparmar19@...il.com> wrote:
> > >
> > > The Infineon TLV493D is a Low-Power 3D Magnetic Sensor. The Sensor
> > > applications includes joysticks, control elements (white goods,
> > > multifunction knops), or electric meters (anti tampering) and any
> > > other application that requires accurate angular measurements at
> > > low power consumptions.
> > >
> > > The Sensor is configured over I2C, and as part of Sensor measurement
> > > data it provides 3-Axis magnetic fields and temperature core measurement.
> > >
> > > The driver supports raw value read and buffered input via external trigger
> > > to allow streaming values with the same sensing timestamp.
> > >
> > > While sensor has interrupt pin multiplexed with I2C SCL pin. But for bus
> >
> > the sensor
> > an interrupt
> > an I2C
> >
> > > configurations interrupt(INT) is not recommended, unless timing constraints
> > > between I2C data transfers and interrupt pulses are monitored and aligned.
> > >
> > > The Sensor's I2C register map and mode information is described in product
> > > User Manual[Link].
> >
> > Replace Link here with 1...
> >
> > > Datasheet: https://www.infineon.com/assets/row/public/documents/24/49/infineon-tlv493d-a1b6-datasheet-en.pdf
> > > Link: https://www.mouser.com/pdfDocs/Infineon-TLV493D-A1B6_3DMagnetic-UserManual-v01_03-EN.pdf
> >
> > ...and add space followed by [1] here.

Note, my above comment also applies to the actual patch.

...

> > > Changes in v2:
> > > - Drop regmap implementation in favor of using direct i2c APIs to
> > >   have uniform communication APIs across the driver.
> >
> > This I don't understand. I mean the motivation behind this. Usually
> > direct I2C communication is used to do some initial checks and
> > configuration and rarely for the actuall run-time driver
> > functionality. Otherwise it means that the regmap may be used with a
> > customised read and write methods.
>
> This was my suggestion.  The device has very odd characteristics that
> means writes really are not register based.  You have to write them all
> every time with now addressing.
>
> So to me regmap just wasn't a good choice here. You could do something
> some nasty stuff to hammer it into a custom regmap, but to me it's just
> not a good fit.

I see, thanks for explaining this to me. Okay, let's leave for now
with the direct use of I2C APIs.


-- 
With Best Regards,
Andy Shevchenko