From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Daney Subject: Re: [PATCH 1/2] i2c: mux: add device tree support Date: Mon, 23 Apr 2012 10:11:33 -0700 Message-ID: <4F958D45.1080800@gmail.com> References: <1334688545-8465-1-git-send-email-swarren@wwwdotorg.org> <20120423111507.GF19192@pengutronix.de> <4F957F9F.7000309@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4F957F9F.7000309-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren Cc: Wolfram Sang , Grant Likely , Rob Herring , Ben Dooks , Linus Walleij , devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Stephen Warren , Lars-Peter Clausen List-Id: linux-i2c@vger.kernel.org On 04/23/2012 09:13 AM, Stephen Warren wrote: > 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 >>> >>> * 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 >> >> David Daney (CCed) posted another variant [1]. Just looking at the >> patches (and not really using them), I tend to like the approach using >> 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. > It was arrived at by iterating through several versions with Grant and Rob. You make at least the third person (after me and Lars-Peter Clausen) wanting to use the device tree to configure the I2C muxes. So at a minimum, it shows a need for this. David Daney. > 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.