Re: [PATCH 1/2] i2c: mux: add device tree support

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 04/23/2012 05:15 AM, Wolfram Sang wrote:
> On Tue, Apr 17, 2012 at 12:49:04PM -0600, Stephen Warren wrote:
>> From: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>
>> * Define core portions of the DT binding for I2C bus muxes.
>> * Enhance i2c_add_mux_adapter():
>> ** Add parameters required for DT support. Update all callers.
>> ** Set the appropriate adap->dev.of_node for the child bus.
>> ** Call of_i2c_register_devices() for the child bus.
>>
>> Signed-off-by: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> 
> David Daney (CCed) posted another variant [1]. Just looking at the
> patches (and not really using them), I tend to like the approach using
> <reg> better. But I am open for discussion, so I'd appreciate your
> feedback.
> 
> Regards,
> 
>    Wolfram
> 
> [1] http://lkml.org/lkml/2012/4/12/423

Ah, that does look like a reasonable binding.

I had meant to call out to reviewers the potentially unusual use of
explicitly named sub-nodes, rather than using the usual reg-based matching.

The main reason I chose named sub-nodes for the busses was so the
sub-nodes would match the pinctrl named states. However, I think we can
make the pinctrl numbering match rather than the pinctrl naming instead.
The only issue is the "idle" state; if we allow it to exist anywhere in
the pinctrl-names list, it'll make the pinctrl numbering mismatch the
sub-node numbering. I think we can solve this by forcing the idle state
to be listed last in pinctrl-names (if it's listed at all). I'll update
my patches based on that David's patch.