Re: [PATCH v3 1/2] dt-bindings: iio: adc: adding support for PAC193X

From: Conor Dooley <conor@kernel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: marius.cristea@microchip.com, jic23@kernel.org, lars@metafoo.de,
	robh+dt@kernel.org, jdelvare@suse.com, linux@roeck-us.net,
	linux-hwmon@vger.kernel.org, krzysztof.kozlowski+dt@linaro.org,
	conor+dt@kernel.org, linux-iio@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] dt-bindings: iio: adc: adding support for PAC193X
Date: Thu, 16 Nov 2023 21:31:42 +0000	[thread overview]
Message-ID: <20231116-uncork-onscreen-d041bbe3bb3f@squawk> (raw)
In-Reply-To: <9d0749ee-08e5-4630-b1b4-27d6aa436b29@linaro.org>

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On Thu, Nov 16, 2023 at 09:00:50PM +0100, Krzysztof Kozlowski wrote:
> On 16/11/2023 19:21, Conor Dooley wrote:
> 
> >>> +allOf:
> >>> +  - if:
> >>> +      properties:
> >>> +        compatible:
> >>> +          contains:
> >>> +            const: interrupts
> >>
> >>
> >> I don't understand what do you want to say here. I am also 100% sure you
> >> did not test it on a real case (maybe example passes but nothing more).
> > 
> > As far as I understand, the same pin on the device is used for both an
> > output or an input depending on the configuration. As an input, it is
> > the "slow-io" control, and as an output it is an interrupt.
> > I think Marius is trying to convey that either this pin can be in
> > exclusively one state or another.
> > 
> > _However_ I am not sure that that is really the right thing to do - they
> > might well be mutually exclusive modes, but I think the decision can be
> > made at runtime, rather than at devicetree creation time. Say for
> > example the GPIO controller this is connected to is capable of acting as
> > an interrupt controller. Unless I am misunderstanding the runtime
> > configurability of this hardware, I think it is possible to actually
> > provide a "slow-io-gpios" and an interrupt property & let the operating
> > system decide at runtime which mode it wants to work in.
> > 
> > I'm off travelling at the moment Marius, but I should be back in work on
> > Monday if you want to have a chat about it & explain a bit more to me?
> 
> Sure, but which compatible contains "interrupts"?

Yeah, I did notice that - I figured you understood that that was meant
to not be a check on compatibles, but rather on regular old properties &
the rationale for the mutual exclusion was what you were missing.

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