Subject: Re: New i2c framework
To: None <>
From: None <>
List: tech-kern
Date: 02/19/2002 11:40:11
At 19 Feb 2002 18:52:59 -0000,  wrote:
> I don't see that anywhere in the SMBus specification.

I don't think you see any mention of smart controllers there, either,
do you?  8-)

> A strictly conforming SMBus controller does not need to provide a
> bitbang interface.

I don't know that there's any such thing as a 'strictly conforming'
device.  8-)

At the very least, since:

> In order to communicate to i2c devices, such
> an interface or its equivalent is required.

and you can use some of the same devices on each, and since the
bitbang interface is so stupid, it would be braindead to create a
smart controller that didn't have a bitbang interface.

> Are you advocating
> a SMBus framework that cannot be made to work on SMBus controllers
> that do not provide a bitbang interface?

Yes.  I know of no such controllers, and would love to see an example
of one.  I don't think you'll find one, to be honest.  I'd bet a small
amount of money on it.

(At the worse, for those, you simply can't use certain devices on that
controller, namely, those which require bitbanged commands or special
formats.  On the other hand, if all drivers do byte-by-byte control or
bitbanging by hand, then you can't use any of those drivers in smart
mode on a smart smbus controller...)

> A framework for smart SMBus controllers can be easily built on a more
> general i2c framework.

How do you figure?  you need to expose the well-defined smbus commands
all the way through the interface, or every back-end driver has to
look at the commands that it sees, and try to recognize them as
specific smbus commands.

rather wasteful.