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From: Scott Wood <scottwood@freescale•com>
To: Matt Sealey <matt@genesi-usa•com>
Cc: Tjernlund <tjernlund@tjernlund•se>,
	linuxppc-dev@ozlabs•org, Jean Delvare <khali@linux-fr•org>,
	i2c@lm-sensors•org
Subject: Re: [RFC] Rework of i2c-mpc.c - Freescale i2c driver
Date: Mon, 05 Nov 2007 15:55:43 -0600	[thread overview]
Message-ID: <472F915F.9010400@freescale.com> (raw)
In-Reply-To: <472F9086.2060606@genesi-usa.com>

Matt Sealey wrote:
> Scott Wood wrote:
>> Jon Smirl wrote:
> 
>>>>> cell-index = <1>;
>>>> What is cell-index for?
>>> I was using it to control the bus number, is that the wrong
>>> attribute?
>> 
>> It shouldn't be specified at all -- the hardware has no concept of
>> a device number.
> 
> Well, all i2c devices have a chip id you can probe for,

I meant a controller device number (a.k.a. bus number), which (outside 
of documentation) is purely a Linux invention, and which is what 
cell-index was being used for above.

> as for buses I think cell-index is a holdover from the way the PSC
> code is organised on the MPC5200 for example - if you have multiple
> buses which use the same registers, for example. It's redundant on
> the PSC's for programming because they all use different register
> offsets but if you move to other devices like the GPTs, then it is
> then useful for debugging (it is far more interesting to say GPT1
> than GPT @ offset to match the) and in general for tweaking OTHER
> parts of the chip (for instance the CDM - very relevant!) which use
> single registers to control entire swathes of units.

Right, that's what cell-index is for.  This is different. :-)

-Scott

  reply	other threads:[~2007-11-05 22:03 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-05 15:14 [RFC] Rework of i2c-mpc.c - Freescale i2c driver Jon Smirl
2007-11-05 19:22 ` Matt Sealey
2007-11-05 19:51   ` Jon Smirl
2007-11-05 19:55     ` Scott Wood
2007-11-05 20:04       ` Jon Smirl
2007-11-05 20:06         ` Scott Wood
2007-11-05 20:11   ` Grant Likely
2007-11-05 19:43 ` Scott Wood
2007-11-05 20:30   ` Jon Smirl
2007-11-05 20:51     ` Scott Wood
2007-11-05 21:52       ` Matt Sealey
2007-11-05 21:55         ` Scott Wood [this message]
2007-11-05 23:03           ` Grant Likely
2007-11-06 17:32         ` Jean Delvare
2007-11-06 18:53           ` Matt Sealey
2007-11-06 20:31             ` Jean Delvare
2007-11-06 21:06               ` Matt Sealey
2007-11-05 22:46       ` Grant Likely
2007-11-06  0:33         ` Jon Smirl
2007-11-06 22:20         ` David Gibson
2007-11-06  0:41       ` Jon Smirl
2007-11-06 17:02         ` Scott Wood
2007-11-06  4:25       ` Jon Smirl
2007-11-06  4:40         ` Stephen Rothwell
2007-11-06 19:02           ` Jon Smirl
2007-11-06 22:22             ` David Gibson
2007-11-06 17:29       ` Jean Delvare
2007-11-06 17:36         ` Scott Wood
2007-11-06 18:10           ` Jean Delvare
2007-11-06 18:26             ` Grant Likely
2007-11-06 18:26               ` Grant Likely
2007-11-06 19:34               ` Jean Delvare
2007-11-06 18:29             ` Scott Wood
2007-11-06 17:45         ` Jon Smirl
2007-11-06 18:17           ` Jean Delvare
2007-11-06 19:07             ` Jon Smirl
2007-11-06  1:34   ` Jon Smirl
2007-11-06  2:28     ` Stephen Rothwell
2007-11-05 20:03 ` Grant Likely
2007-11-05 20:41 ` Jon Smirl

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