Thierry,

On Thu, Sep 3, 2015 at 2:39 AM, Thierry Reding [off-list ref] wrote:

Perhaps the I2C core needs to be taught to look at the adapter's
->dev.parent->of_node in of_find_i2c_adapter_by_node(). As I understand
it the purpose for registering a separate struct device for each I2C
controller is so that there's an I2C parent for all slaves. At the same
time every controller sets up ->dev.parent, and that parent's OF node is
what we really want when we look up an I2C adapter by OF node. In other
words, the OF node by which I2C adapters are referenced is always that
of its parent device, as far as I can tell.

Wolfram, do you know of any cases where adapter->dev.of_node would not
be the same as adapter->dev.parent->of_node?

This sounds pretty reasonable to me.  Certainly it would be a pretty
reasonable fallback if adapter->dev.of_node was NULL.

-Doug