Re: [PATCH v5 04/10] dt-bindings: i3c: Document core bindings

[Boris Brezillon]

On Wed, 11 Jul 2018 16:10:10 +0200
Arnd Bergmann <arnd@xxxxxxxx> wrote:

> On Fri, Jun 22, 2018 at 12:49 PM, Boris Brezillon
> <boris.brezillon@xxxxxxxxxxx> 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.