From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp03.au.ibm.com (E23SMTP03.au.ibm.com [202.81.18.172]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp03.au.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 3CFBFDDF77 for ; Fri, 6 Jun 2008 11:10:41 +1000 (EST) Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.18.234]) by e23smtp03.au.ibm.com (8.13.1/8.13.1) with ESMTP id m5619k5e007546 for ; Fri, 6 Jun 2008 11:09:46 +1000 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m561ALmT3268846 for ; Fri, 6 Jun 2008 11:10:21 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m561AcKW017016 for ; Fri, 6 Jun 2008 11:10:38 +1000 Date: Thu, 5 Jun 2008 12:41:40 +1000 From: David Gibson To: Josh Boyer Subject: Re: "cell-index" vs. "index" vs. no index in I2C device nodes Message-ID: <20080605024140.GA30980@yookeroo.seuss> References: <200806041706.21557.sr@denx.de> <4846B39F.3010601@freescale.com> <20080604154351.GB10393@ld0162-tx32.am.freescale.net> <20080604211942.2bddc860@zod.rchland.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20080604211942.2bddc860@zod.rchland.ibm.com> Cc: Scott Wood , linuxppc-dev@ozlabs.org, Stefan Roese , Timur Tabi List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Jun 04, 2008 at 09:19:42PM -0500, Josh Boyer wrote: > On Wed, 4 Jun 2008 10:43:51 -0500 > Scott Wood wrote: > > > On Wed, Jun 04, 2008 at 10:24:15AM -0500, Timur Tabi wrote: > > > Stefan Roese wrote: > > > > I'm wondering what is currently recommended in the I2C device tree nodes? The > > > > current IBM I2C driver (i2c-ibm_iic.c) checks "index" and most FSL dts files > > > > use "cell-index". Some 4xx dts files implement "cell-index" some have no > > > > index at all. > > > > > > > > So what should be used here. Please advise and I'll prepare a patch for it. > > > > > > I just posted a patch for the FSL I2C driver to check for cell-index. I'm under > > > the impression that cell-index is the standard for enumerating devices in the > > > device tree. > > > > No, it's the standard for correlating devices with portions of a shared > > register block elsewhere. Your use in the I2C node is merely a hack to > > deal with Linux wanting to deal with indices rather than pointers, > > combined with a lack of a decent way to look up a device struct from the > > device node. > > So if possible, I'd like to eliminate the *index stuff all together > from the 4xx driver. The private data structure contains an idx > parameter, but this can be populated based on probe order or something. > > >From a device tree perspective, index and cell-index are both > incorrect. The IIC macros don't share register blocks with anything, > are enumerated as unique instances per macro in the device tree, and > should be able to be distinguished by "regs" and/or unit address. > > Does anyone disagree with that? Hear, hear. Aliases can also provide a reasonable way of enumerating devices, if "reg" isn't suitable on its own. Though obviously, drivers will need some sort of fallback if suitable aliases don't exist in the tree. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson