Re: [RFC][PATCH 08/30] powerpc/85xx: Rework P1020 SoC device tree

On Nov 10, 2011, at 12:05 PM, Scott Wood wrote:

On Thu, Nov 10, 2011 at 10:13:51AM -0600, Kumar Gala wrote:

quoted

Split the P1020 SoC device tree into what we can include as a =

'prefix'

quoted

to the board device tree and what needs to be included as a =

'postfix'.

quoted

=20
This allows use more re-use and less duplication between various =

board

quoted

device tree configurations (32-bit address map vs 36-bit address =

map).

=20
Could you elaborate on the issues that require this pre/post approach?

We utilize two 'features' of dtc to accomplish things.  One is includes =
the other is 'merging of labeled nodes'.

We can using merging to allow the board to specify the "reg" & "ranges" =
values of a SoC node that might vary between physical address maps =
(32-bit vs 36-bit as example).

dtc is able to 'merge' multiple labeled nodes as well.  So we use that =
to handle board specific values for something like localbus if we want =
to support both a 32-bit and 36-bit address map.

What does the SoC part need to specify that has to override or go =

within

something the board specifies?

Not sure I follow the question.

- k=