Subject: Re: i2c 10-bit addressing support
To: Garrett D'Amore <>
From: Garrett D'Amore <>
List: tech-kern
Date: 07/14/2006 09:34:34
Allen Briggs wrote:
> On Thu, Jul 13, 2006 at 03:42:04PM -0700, Garrett D'Amore wrote:
>> This adds full addressing (10-bit) support to the i2c bitbang support in
>> NetBSD.  I don't have any 10-bit devices, so I cannot test, but it
>> doesn't seem to break 7-bit addressing at least:
> My only minor concern is if we should be explicitly disallowing
> the 10-bit address prefix.  Isn't that a legal address for 7-bit
> systems, however unlikely it is that someone would use it?

Not according to the spec.  The address is reserved for use as a 10-bit

> If I'm wrong, just tell me.  :-)
> If I'm right, it seems like there should be a diagnostic warning
> message if someone tries to access a device at that address.  It's
> not like the devices move around (at least not in any system I've
> played with).

Maybe we should warn on error if code tries to use this prefix, as the
code would have to be buggy.  (I suppose it is possible that someone
created a device that uses this reserved address, but that device would
not be compliant, and it would have to be particularly poor judgement.)

    -- Garrett
> -allen

Garrett D'Amore, Principal Software Engineer
Tadpole Computer / Computing Technologies Division,
General Dynamics C4 Systems
Phone: 951 325-2134  Fax: 951 325-2191