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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 11 Jul 2018 16:56:41 +0200
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Subject: Re: [PATCH v5 04/10] dt-bindings: i3c: Document core bindings
To:     Boris Brezillon <boris.brezillon@bootlin.com>
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On Wed, Jul 11, 2018 at 4:45 PM, Boris Brezillon
<boris.brezillon@bootlin.com> wrote:
> On Wed, 11 Jul 2018 16:10:10 +0200
> Arnd Bergmann <arnd@arndb.de> wrote:
>
>> On Fri, Jun 22, 2018 at 12:49 PM, Boris Brezillon
>> <boris.brezillon@bootlin.com> wrote:
>> > A new I3C subsystem has been added and a generic description has been
>> > created to represent the I3C bus and the devices connected on it.
>> >
>>
>> > +I2C devices
>> > +===========
>> > +
>> > +Each I2C device connected to the bus should be described in a subnode. All
>> > +properties described in Documentation/devicetree/bindings/i2c/i2c.txt are
>> > +valid here, but several new properties have been added.
>> > +
>> > +New constraint on existing properties:
>> > +--------------------------------------
>> ...
>> > +  + third cell: should be 0
>>
>> What for? Just to be future-proof, or do you have something specific
>> in mind here?
>
> Even if I2C devices only need 1 cell, I3C devices need 3 (1 for the
> static address and 2 for the PID). Since both type of devices are
> described under the same bus node, and we can have different
> #address-cells, I had to put 0-padding in the last cell.

Ok, got it.

    Arnd