[PATCH][v2] powerpc/fsl-booke: Add T1040D4RDB/T1042D4RDB board support

[Priyanka Jain]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Friday, July 17, 2015 10:37 PM
> To: Jain Priyanka-B32167
> Cc: linuxppc-dev at lists.ozlabs.org
> Subject: Re: [PATCH][v2] powerpc/fsl-booke: Add T1040D4RDB/T1042D4RDB
> board support
> 
> On Fri, 2015-07-17 at 01:17 -0500, Jain Priyanka-B32167 wrote:
> >
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Friday, July 17, 2015 1:06 AM
> > > To: Jain Priyanka-B32167
> > > Cc: linuxppc-dev at lists.ozlabs.org
> > > Subject: Re: [PATCH][v2] powerpc/fsl-booke: Add
> > > T1040D4RDB/T1042D4RDB board support
> > >
> > > > > +                i2c at 118100{
> > > > > +                      mux at 77{
> > > > > +                             compatible = "nxp,pca9546";
> > > > > +                             reg = <0x77>;
> > > > > +                             #address-cells = <1>;
> > > > > +                             #size-cells = <0>;
> > > > > +                     };
> > > > > +             };
> > > >
> > > > A mux with no nodes under it (and yet it has #address-cells/#size-
> > > > cells)?
> > > > What is it multiplexing?
> > > > [Priyanka]: PCA9546 is i2c mux device , to which other i2c devices
> > > > (up-to 8
> > > > ) can be further connected on output channels On T104xD4RDB,
> > > > channel 0, 1, 3 line are connected to PEX device, Channel 2 to
> > > > hdmi interface (initialization is done in u-boot only), other channels are
> grounded.
> > > > So, as such Linux is not using the second level I2C devices
> > > > connected on this MUX device. So, I have not shown next level
> hierarchy.
> > > > Should I replace 'mux' with some other name? . Please suggest.
> > >
> > > The device tree describes the hardware, not just what Linux uses...
> > > but what I don't understand is why you describe the mux at all if
> > > you're not going to describe what goes underneath it.
> > >
> > [Jain Priyanka-B32167] : Is below looks OK?
> > i2c at 118100{
> >  +                      i2c at 77{
> >  +                             compatible = "nxp,pca9546";
> >  +                             reg = <0x77>;
> >  +                             #address-cells = <1>;
> >  +                             #size-cells = <0>;
> >  +                     };
> >  +             };
> 
> Where in my above comment did it appear that I was complaining about the
> node name?
> 
[Jain Priyanka-B32167]
From what I understand:
PCA9546 is a mux device and it would be good if we were able to present the I2C devices on output lines as subnodes like in case of B4qds board and then 'mux' name would have make more sense.
But in case of T1040D4RDB board, output i2c lines are going to PEX slots, PCI connector. I am not aware of how to represents them as sub-nodes in dts.
> -Scott