Re: [RFC] Rework of i2c-mpc.c - Freescale i2c driver

[Jean Delvare <khali@linux-fr.org>]

Hi Scott,

On Tue, 06 Nov 2007 11:36:23 -0600, Scott Wood wrote:
> Jean Delvare wrote:
> >>>> We might as well just use i2c_new_device() instead of messing around
> >>>> with bus numbers.  Note that this is technically no longer platform
> >>>> code, so it's harder to justify claiming the static numberspace.
> >>> I was allowing control of the bus number with "cell-index" and
> >>> i2c_add_numbered_adapter().
> >>> Should I get rid of this and switch to i2c_add_adapter()?
> >> Yes.
> > 
> > No! If you don't call i2c_add_numbered_adapter() then new-style i2c
> > clients will never work on your i2c adapter.
> 
> I thought that was what i2c_new_device() was for?

Sorry, I've not been completely clear. Yes, you can use
i2c_new_device() on an adapter that has been added with
i2c_add_adapter(). However, this requires that you have a reference to
that i2c_adapter, which is usually not the case with system-wide I2C
buses. Embedded platforms would rather use i2c_add_numbered_adapter(),
give a list of chips to i2c_register_board_info() and let i2c-core
instantiate them. i2c_new_device was primarily meant for multimedia
adapters.

> By handling all the device tree stuff in the driver, it acts more like 
> an add-on adapter than a platform device.

-- 
Jean Delvare