linux-kernel - Re: [PATCH v6 4/7] dt-bindings: iio: accel: adxl345: make interrupts not a required property

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Message-ID: <CAFXKEHatgV9gYVCvcxmjce9qcHtVLhvQuuSuC7rxtqFa5XLtMg@mail.gmail.com>
Date: Fri, 13 Dec 2024 09:06:39 +0100
From: Lothar Rubusch <l.rubusch@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: lars@...afoo.de, Michael.Hennerich@...log.com, jic23@...nel.org, 
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	devicetree@...r.kernel.org, linux-iio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, eraretuya@...il.com
Subject: Re: [PATCH v6 4/7] dt-bindings: iio: accel: adxl345: make interrupts
 not a required property

On Thu, Dec 12, 2024 at 9:11 AM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>
> On Wed, Dec 11, 2024 at 11:06:45PM +0000, Lothar Rubusch wrote:
> > Remove interrupts from the list of required properties. The ADXL345
> > provides two interrupt lines. Anyway, the interrupts are an option, to
> > be used for additional event features. The driver can measure without
> > interrupts. Hence, interrupts should never have been required for the
> > ADXL345. Thus having interrupts required can be considered to be a
> > mistake.
>
> Partially this explains my question on previous patch, so consider
> reordering them.
>

I understand.

> And with combined knowledge, your driver now depends on interrupt names
> to setup interrupts. "interrupts" property alone is not sufficient, so
> you should encode it in the binding and explain in rationale why this is
> required (it is a change in ABI).
>
> https://elixir.bootlin.com/linux/v6.8-rc3/source/Documentation/devicetree/bindings/example-schema.yaml#L193
>

The accelerometer does not need interrupts connected/configured for
basic functionality. Interrupt declaration allows for additional
features. Then there are two possible interrupt lines, only one is
connected. Thus, either only one INT out of two, or none needs to be
configured in the DT depending on the hardware setup. This also needs
to be configured then in the sensor, which INT line to use for
signalling. Thus we need the information if INT1 or INT2 was setup, if
any.

Hence, configuring an "interrupts" property only makes sense, if also
a "interrupt-names" is configured, and vice versa. None of them are
required for basic accelerometer functionality.

Thank you so much for providing me the link to the annotated
example-schema. I'll try then to set vice versa dependency of
interrupts and interrupt-names and hope.. I'm sure you'll let me know
right away if I'm doing something wrong.

Seriously, thanks the link is really helpful!
Best,
L

> Best regards,
> Krzysztof
>