From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757415Ab2ARUVD (ORCPT ); Wed, 18 Jan 2012 15:21:03 -0500 Received: from mail-gy0-f174.google.com ([209.85.160.174]:44949 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755924Ab2ARUVB (ORCPT ); Wed, 18 Jan 2012 15:21:01 -0500 Date: Wed, 18 Jan 2012 13:20:57 -0700 From: Grant Likely To: Tony Lindgren Cc: Shawn Guo , "linus.walleij@stericsson.com" , "devicetree-discuss@lists.ozlabs.org" , "s.hauer@pengutronix.de" , "linux-kernel@vger.kernel.org" , "rob.herring@calxeda.com" , "kernel@pengutronix.de" , "cjb@laptop.org" , "linux-arm-kernel@lists.infradead.org" , Dong Aisheng Subject: Re: Pinmux bindings proposal Message-ID: <20120118202057.GH4223@ponder.secretlab.ca> References: <74CDBE0F657A3D45AFBB94109FB122FF17801D202F@HQMAIL01.nvidia.com> <20120116182808.GG4223@ponder.secretlab.ca> <20120118141329.GA22818@atomide.com> <20120118153256.GB22818@atomide.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20120118153256.GB22818@atomide.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 18, 2012 at 07:32:56AM -0800, Tony Lindgren wrote: > * Shawn Guo [120118 05:57]: > > On 18 January 2012 22:13, Tony Lindgren wrote: > > > Hi, > > > > > > * Grant Likely [120116 09:55]: > > >> On Fri, Jan 13, 2012 at 12:39:42PM -0800, Stephen Warren wrote: > > >> >                 pinmux = > > >> >                         <"default" &pmx_sdhci_active> > > >> >                         <"suspend" &pmx_sdhci_suspend>; > > >> > > > >> >                 /* 1:n example: */ > > >> >                 pinmux = > > >> >                         <"default" &pmx_sdhci_mux_a> > > >> >                         <"default" &pmx_sdhci_pincfg_a> > > >> >                         <"suspend" &pmx_sdhci_mux_a> > > >> >                         <"suspend" &pmx_sdhci_pincfg_a_suspend>; > > >> > > >> > > >> Yeah, don't do this.  Mixing phandle, string and cell values in a > > >> property gets messy and could become troublesome to parse.  I've > > >> backed away from it in the clk binding. > > > > > > Yup, that's because the string is embedded directly into the mixed > > > mode array and will likely make the following data unaligned. That > > > means it's extremely flakey to parse, and will lead into horrible > > > errors if you have typos in the .dts file.. Tried that and gave up > > > on it. > > > > > > I think I've found a way to avoid using names at all, assuming we set > > > each pin as a phandle for the drivers to use :) > > > > > The problem with doing that is we will have to represent each pin as a > > node in device tree. For imx6q case, we have 197 pins. Doing so will > > bloat the device tree. > > Sure there's some overhead. I've got it working with 220 pins, it's > not too bad as threre's not much string parsing involved. > > I don't have all the devices mapping the pins though. The .dtb for > omap4 is about 25k now. > > If we wanted to avoid adding phandles for each pin, then we could do: > > serial@0x48020000 { > compatible = "ti,8250"; > reg = <0x48020000 0x100>; > reg-shift = <2>; > interrupts = <106>; > > /* controller, offset, value */ > pins = <&mux1 0xabcd 0x10 > &mux1 0xabcf 0x0>; > }; > > But then the .dts file becomes an unreadable matrix unless we have > a preprocessor.. One node per pin does get excessive in a hurry. I prefer the one node per pin controller. Tools can be written to make writing the definition easier. g.