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

Jean Delvare khali at linux-fr.org
Tue Nov 6 20:34:53 CET 2007


On Tue, 6 Nov 2007 11:26:14 -0700, Grant Likely wrote:
> On 11/6/07, Jean Delvare <khali at linux-fr.org> wrote:
> > 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.
> 
> *Some* embedded platforms would rather use i2c_add_numbered_adapter().  :-)
> 
> On powerpc, and other platforms which have a device tree, we don't
> need to define a table of devices in the platform code because we've
> already got a rich structure for describing such things.  The i2c
> busses and i2c devices are grouped together in the device tree, so
> when the i2c bus is probed, it should call out to common i2c device
> tree parsing code to instantiate all the devices described in the
> tree.
> 
> It would be awkward to describe the i2c bus in the device tree but
> still have to use a static structure to describe the devices on that
> bus.

Ah, OK, thanks for the clarification. Then indeed using
i2c_add_adapter() will work fine, agreed.

-- 
Jean Delvare



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