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Date: Mon, 23 Apr 2012 10:13:19 -0600
From: Stephen Warren <swarren@wwwdotorg.org>
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To: Wolfram Sang <w.sang@pengutronix.de>
CC: Grant Likely <grant.likely@secretlab.ca>,
        Rob Herring <rob.herring@calxeda.com>, Ben Dooks <ben-linux@fluff.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        devicetree-discuss@lists.ozlabs.org, linux-i2c@vger.kernel.org,
        linux-kernel@vger.kernel.org, Stephen Warren <swarren@nvidia.com>,
        David Daney <ddaney.cavm@gmail.com>
Subject: Re: [PATCH 1/2] i2c: mux: add device tree support
References: <1334688545-8465-1-git-send-email-swarren@wwwdotorg.org> <20120423111507.GF19192@pengutronix.de>
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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@nvidia.com>
>>
>> * 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@nvidia.com>
> 
> 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.

From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Subject: Re: [PATCH 1/2] i2c: mux: add device tree support
Date: Mon, 23 Apr 2012 10:13:19 -0600
Message-ID: <4F957F9F.7000309@wwwdotorg.org>
References: <1334688545-8465-1-git-send-email-swarren@wwwdotorg.org> <20120423111507.GF19192@pengutronix.de>
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To: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>, Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>, Ben Dooks <ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>, Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, David Daney <ddaney.cavm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
List-Id: devicetree@vger.kernel.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.