From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Message-ID: <17700.20834.792693.853677@cargo.ozlabs.ibm.com> Date: Thu, 5 Oct 2006 10:27:14 +1000 From: Paul Mackerras To: Dan Malek Subject: Re: [PATCH 10/11] Add MPC8360EMDS board support In-Reply-To: <2867EA41-5135-43F7-9873-044C617EAC1B@embeddedalley.com> References: <20060927155626.4d5ca19c@vitb.ru.mvista.com> <4879B0C6C249214CBE7AB04453F84E4D19D865@zch01exm20.fsl.freescale.net> <20060927165556.04c8d5d7@vitb.ru.mvista.com> <20060927112201.293fef44@localhost.localdomain> <17699.769.632098.479906@cargo.ozlabs.ibm.com> <2867EA41-5135-43F7-9873-044C617EAC1B@embeddedalley.com> Cc: Olof Johansson , linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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.