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From: Scott Wood <scottwood@freescale•com>
To: Grant Likely <grant.likely@secretlab•ca>
Cc: Jean Delvare <khali@linux-fr•org>,
	linuxppc-dev@ozlabs•org, Stefan Roese <sr@denx•de>,
	i2c@lm-sensors•org
Subject: Re: [PATCH 2/2] i2c: Add devtree-aware iic support for PPC4xx
Date: Mon, 15 Oct 2007 14:54:39 -0500	[thread overview]
Message-ID: <4713C57F.7060509@freescale.com> (raw)
In-Reply-To: <fa686aa40710151248y5e921a4fmbb0a3e0b7c9a2ca5@mail.gmail.com>

Grant Likely wrote:
> On 10/15/07, Scott Wood <scottwood@freescale•com> wrote:
>> For associating a device node with a human readable label, I'd
>> prefer a "label" property in the device node, rather than doing it
>> backwards with aliases.
> 
> Here the corresponding problem; having to scan every device node to 
> make sure you don't assign a number already selected by another node 
> (in the case where one node is assigned a number and another is not).
> 
Don't Do That(tm).  If you use this mechanism, and an adapter node
doesn't have a bus number, then it doesn't get to pre-register devices,
but instead must use i2c_new_device.

>>> As per your point below; if all the i2c devices are children of
>>> the adapter, then yes you are right that the bus number doesn't
>>> matter to the user.  But it *does* matter for things like serial
>>> and ethernet ports.
>> And a label property would be great for that. :-)
> 
> Not really; if the user needs to renumber devices; you don't want him
>  fiddling around in the hardware description.

Why would the user renumber devices?

> Just like the chosen node; an aliases describes logical constructs,
> not physical ones.  I don't think this is any different from the
> linux,stdout-path property in chosen.

Well, it's somewhat different in that stdout describes a usage of the 
device, not the identity.

Still, I don't like linux,stdout-path. :-)
At the very least it should be a phandle.

-Scott

  reply	other threads:[~2007-10-15 20:03 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-15 13:29 [PATCH 2/2] i2c: Add devtree-aware iic support for PPC4xx Stefan Roese
2007-10-15 16:32 ` Eugene Surovegin
2007-10-15 16:57   ` Grant Likely
2007-10-15 18:53     ` Scott Wood
2007-10-15 19:11       ` Eugene Surovegin
2007-10-15 19:16         ` Grant Likely
2007-10-15 19:18         ` Scott Wood
2007-10-15 19:13       ` Grant Likely
2007-10-15 19:24         ` Scott Wood
2007-10-15 19:48           ` Grant Likely
2007-10-15 19:54             ` Scott Wood [this message]
2007-10-15 20:26               ` Grant Likely
2007-10-15 20:45                 ` Scott Wood
2007-10-16  3:20         ` David Gibson
2007-10-16  4:21           ` Grant Likely
2007-10-16 19:19             ` Jean Delvare
2007-10-17  0:37               ` David Gibson
2007-10-15 16:46 ` Grant Likely
2007-10-19 11:56 ` Valentine Barshak

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