Subject: Re: [PATCH 1/4] [POWERPC] 85xx: add board support for the TQM8548 modules

From: Wolfgang Grandegger <[email-masked]>
Date: Mon, 02 Jun 2008 08:31:40 +0200

David Gibson wrote:
> On Fri, May 30, 2008 at 08:49:45AM +0200, Wolfgang Grandegger wrote:
>> This patch adds support for the TQM8548 modules from TQ-Components
>> GmbH (http://www.tqc.de).
> 
> [snip]
>> index 0000000..d09250a
>> --- /dev/null
>> +++ b/arch/powerpc/boot/dts/tqm8548.dts
>> @@ -0,0 +1,370 @@
>> +/*
>> + * TQM8548 Device Tree Source
>> + *
>> + * Copyright 2006 Freescale Semiconductor Inc.
>> + * Copyright 2008 Wolfgang Grandegger <[email-masked]>
>> + *
>> + * This program is free software; you can redistribute  it and/or modify it
>> + * under  the terms of  the GNU General  Public License as published by the
>> + * Free Software Foundation;  either version 2 of the  License, or (at your
>> + * option) any later version.
>> + */
>> +
>> +/dts-v1/;
> 
> [snip]
>> +		i2c@3000 {
>> +			#address-cells = <1>;
>> +			#size-cells = <0>;
>> +			cell-index = <0>;
> [...]
>> +		enet0: ethernet@24000 {
>> +			cell-index = <0>;
> [...]
>> +		serial0: serial@4500 {
>> +			cell-index = <0>;
> [...]
>> +	pci0: pci@e0008000 {
>> +		cell-index = <0>;
> 
> You have a whole lot of 'cell-index' properties through both these
> trees, and they all look wrong.  cell-index is a hack, which should be
> avoided wherever practical - it should only be used when the index is
> used to offset into some global register block, never simply to
> differentiate (use reg for that) or name the devices (use aliases for
> that).

OK, I can remove them from the TQM85*.dts files but I think the problem
is more general. It seems to be frequently used for similar purposes,
also in the code, at least in 2.6.26-rc4:

  $ cd linux-2.6/arch/powerpc/boot/dts
  $ grep -l 'cell-index' *.dts | wc -l
  58

Wolfgang