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Date:   Thu, 17 Nov 2022 16:51:38 +0000
From:   Jonathan Cameron <Jonathan.Cameron@huawei.com>
To:     Gerald Loacker <gerald.loacker@wolfvision.net>
CC:     <linux-iio@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Nikita Yushchenko <nikita.yoush@cogentembedded.com>,
        Jakob Hauser <jahau@rocketmail.com>,
        Michael Riesch <michael.riesch@wolfvision.net>
Subject: Re: [PATCH 1/2] dt-bindings: iio: magnetometer: add ti tmag5273
 documentation file
Message-ID: <20221117165138.000012a0@huawei.com>
In-Reply-To: <f52dcb6d-30ec-3d49-7e28-9761462d4799@wolfvision.net>
References: <20221115073718.2377311-1-gerald.loacker@wolfvision.net>
        <20221115073718.2377311-2-gerald.loacker@wolfvision.net>
        <20221115174355.00004a01@Huawei.com>
        <f52dcb6d-30ec-3d49-7e28-9761462d4799@wolfvision.net>
Organization: Huawei Technologies R&D (UK) Ltd.
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On Thu, 17 Nov 2022 17:12:33 +0100
Gerald Loacker <gerald.loacker@wolfvision.net> wrote:

> Am 15.11.2022 um 18:43 schrieb Jonathan Cameron:
> > On Tue, 15 Nov 2022 08:37:17 +0100
> > Gerald Loacker <gerald.loacker@wolfvision.net> wrote:
> >   
> >> Add bindings documentation file for TI TMAG5273.
> >>
> >> Signed-off-by: Gerald Loacker <gerald.loacker@wolfvision.net>
> >> ---
> >>  .../iio/magnetometer/ti,tmag5273.yaml         | 72 +++++++++++++++++++
> >>  MAINTAINERS                                   |  6 ++
> >>  2 files changed, 78 insertions(+)
> >>  create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/ti,tmag5273.yaml
> >>
> >> diff --git a/Documentation/devicetree/bindings/iio/magnetometer/ti,tmag5273.yaml b/Documentation/devicetree/bindings/iio/magnetometer/ti,tmag5273.yaml
> >> new file mode 100644
> >> index 000000000000..2f5b0a4d2f40
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/iio/magnetometer/ti,tmag5273.yaml
> >> @@ -0,0 +1,72 @@
> >> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> >> +%YAML 1.2
> >> +---
> >> +$id: https://eur04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fschemas%2Fiio%2Fmagnetometer%2Fti%2Ctmag5273.yaml%23&amp;data=05%7C01%7Cgerald.loacker%40wolfvision.net%7C9788e9788f344fcff9b808dac730f926%7Ce94ec9da9183471e83b351baa8eb804f%7C1%7C0%7C638041310400330990%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=nczO1QC74gD6eGXAkm%2B6LRrc7fyEsr62r%2B3aoW%2Bcfu4%3D&amp;reserved=0
> >> +$schema: https://eur04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fmeta-schemas%2Fcore.yaml%23&amp;data=05%7C01%7Cgerald.loacker%40wolfvision.net%7C9788e9788f344fcff9b808dac730f926%7Ce94ec9da9183471e83b351baa8eb804f%7C1%7C0%7C638041310400330990%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=raKUiSntfhvdSSnqiR1Wm%2Fqr9cI3XEu5HCprqvISlLE%3D&amp;reserved=0
> >> +
> >> +title: TI TMAG5273 Low-Power Linear 3D Hall-Effect Sensor
> >> +
> >> +maintainers:
> >> +  - Gerald Loacker <gerald.loacker@wolfvision.net>
> >> +
> >> +description:
> >> +  The TI TMAG5273 is a low-power linear 3D Hall-effect sensor. This device
> >> +  integrates three independent Hall-effect sensors in the X, Y, and Z axes.
> >> +  The device has an integrated temperature sensor available. The TMAG5273
> >> +  can be configured through the I2C interface to enable any combination of
> >> +  magnetic axes and temperature measurements. An integrated angle calculation
> >> +  engine (CORDIC) provides full 360? angular position information for both
> >> +  on-axis and off-axis angle measurement topologies. The angle calculation is
> >> +  performed using two user-selected magnetic axes.
> >> +
> >> +properties:
> >> +  $nodename:
> >> +    pattern: '^magnetometer@[0-9a-f]+$'  
> > 
> > What Krzysztof said on this ;)
> >   
> >> +
> >> +  compatible:
> >> +    const: ti,tmag5273
> >> +
> >> +  reg:
> >> +    maxItems: 1
> >> +
> >> +  "#io-channel-cells":
> >> +    const: 1
> >> +
> >> +  ti,angle-enable:
> >> +    description:
> >> +      Enables angle measurement in the selected plane.
> >> +      0 = OFF
> >> +      1 = X-Y (default)
> >> +      2 = Y-Z
> >> +      3 = X-Z  
> > 
> > This feels like something we should be configuring at runtime rather that
> > DT, or is it driven by board design or similar?
> >   
> 
> We use this sensor for a zoom wheel application, there is an EVM from TI
> for this as well. So this is for setting the mounting position of the wheel.

Ok. Thanks for explanation. Makes sense.

> 
> >> +    $ref: /schemas/types.yaml#/definitions/uint32
> >> +    minimum: 0
> >> +    maximum: 3
> >> +
> >> +  vcc-supply:
> >> +    description:
> >> +      A regulator providing 1.7 V to 3.6 V supply voltage on the VCC pin,
> >> +      typically 3.3 V.
> >> +  
> > 
> > The dt binding should attempt to describe the hardware, not what we happen
> > to support in the driver so far. So I'd expect to also see an interrupt.
> > That way if someone ships a dts file today, and we enable it sometime in the
> > future they will be ready for it.
> >  
> 
> Is it fine to add just the description without example then? The
> interrupt has many options such as low active or low pulse.

Yes.  Just add description. The details of type etc depend on wiring
to some degree (inverters in the path etc). Nice to add an example later
but for now we can assume anyone who is providing the interrupt set it
up correctly.

Jonathan