Re: [PATCH 10/11] Add MPC8360EMDS board support

[Paul Mackerras <paulus@samba.org>]

Dan Malek writes:

> I'm not against using the device tree (or platform data
> or #defines) when it's appropriate to do so.  I think our
> obsession to represent everything there is what is
> creating the complexity.  If a #define in a board
> specific port file makes sense, then just do that,
> even if it is a BSCR address.

So, where this discussion started was that I saw an ioremap in an
ethernet driver using a physical address defined with #define, and I
said "that should go in the device tree".  And I would still say that
if the ioremap was still there, since the driver is one that is useful
across a range of boards and chips.

My other point would be that what you say is valid *until* the
hardware engineers come to you and say "we're doing rev 2 of the
board, and we had to move the BCSR a bit.  That's OK with you, isn't
it?".

If you have the BCSR address in the device tree, you don't even need
to recompile your kernel.  You can just copy your board.dts to
board-rev2.dts, change the address in there, and rerun the wrapper
script to create the flash image to put on the new board.  Or if you
are using a bootloader that knows how to supply a device-tree blob,
you just put board-rev2.dtb into flash along with your existing kernel
image.

Paul.