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Date:   Fri, 4 Feb 2022 11:36:02 +0100
From:   Alexandre Belloni <alexandre.belloni@bootlin.com>
To:     Eugen.Hristev@microchip.com
Cc:     robh+dt@kernel.org, Nicolas.Ferre@microchip.com,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, clement.leger@bootlin.com
Subject: Re: [PATCH] dt-bindings: microchip: atmel,at91rm9200-tcb: remove
 mandatory interrupts property
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References: <20220204081446.474991-1-eugen.hristev@microchip.com>
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 <e939a0df-052c-43a6-8be6-51848d3fe5e5@microchip.com>
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On 04/02/2022 10:28:43+0000, Eugen.Hristev@microchip.com wrote:
> On 2/4/22 11:46 AM, Alexandre Belloni wrote:
> > On 04/02/2022 10:14:46+0200, Eugen Hristev wrote:
> >> The timer block can be used only to be read and to measure time in a polling
> >> fashion. This can be used by Linux like this for example, or it can be used
> >> by different projects which do not have interrupt controllers, or do not
> >> wish to enable them (e.g. U-boot).
> >> As DT is ABI, the binding should relate to all possible use cases and describe
> >> the hardware and the requirements.
> >> The interrupt is not a hard requirement for the timer to function in a
> >> specific way.
> >> Thus, choose to remove the interrupts property from the mandatory list of
> >> properties.
> >>
> > 
> > The correct hardware description is that the interrupt is present on the
> > IP. Having software behave differently depending on the presence of that
> > property is configuration, not hardware description.
> 
> I agree. The interrupt is present on the IP, thus the property exists 
> and it's described.
> However, the interrupt is not mandatory for IP operations. Thus it 
> should not be in the list of mandatory properties.
> 

If the interrupt is always present, it is mandatory, it doesn't matter
whether is is used or necessary to get the IP to work.


> > 
> >> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> >> ---
> >>   .../devicetree/bindings/soc/microchip/atmel,at91rm9200-tcb.yaml  | 1 -
> >>   1 file changed, 1 deletion(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/soc/microchip/atmel,at91rm9200-tcb.yaml b/Documentation/devicetree/bindings/soc/microchip/atmel,at91rm9200-tcb.yaml
> >> index 597d67fba92f..27f78459b892 100644
> >> --- a/Documentation/devicetree/bindings/soc/microchip/atmel,at91rm9200-tcb.yaml
> >> +++ b/Documentation/devicetree/bindings/soc/microchip/atmel,at91rm9200-tcb.yaml
> >> @@ -134,7 +134,6 @@ allOf:
> >>   required:
> >>     - compatible
> >>     - reg
> >> -  - interrupts
> >>     - clocks
> >>     - clock-names
> >>     - '#address-cells'
> >> --
> >> 2.25.1
> >>
> > 
> > --
> > Alexandre Belloni, co-owner and COO, Bootlin
> > Embedded Linux and Kernel engineering
> > https://bootlin.com
> > 
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com