From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: Pinmux bindings proposal Date: Wed, 18 Jan 2012 07:32:56 -0800 Message-ID: <20120118153256.GB22818@atomide.com> References: <74CDBE0F657A3D45AFBB94109FB122FF17801D202F@HQMAIL01.nvidia.com> <20120116182808.GG4223@ponder.secretlab.ca> <20120118141329.GA22818@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Shawn Guo Cc: Grant Likely , "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 List-Id: devicetree@vger.kernel.org * 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: > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 pinmux =3D > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 <"default" &pmx_sdhci_active> > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 <"suspend" &pmx_sdhci_suspend>; > >> > > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 /* 1:n e= xample: */ > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 pinmux =3D > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 <"default" &pmx_sdhci_mux_a> > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 <"default" &pmx_sdhci_pincfg_a> > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 <"suspend" &pmx_sdhci_mux_a> > >> > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 <"suspend" &pmx_sdhci_pincfg_a_suspend>; > >> > >> > >> Yeah, don't do this. =C2=A0Mixing phandle, string and cell values = in a > >> property gets messy and could become troublesome to parse. =C2=A0I= '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 s= et > > 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 wil= l > 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 =3D "ti,8250"; reg =3D <0x48020000 0x100>; reg-shift =3D <2>; interrupts =3D <106>; /* controller, offset, value */ pins =3D <&mux1 0xabcd 0x10 &mux1 0xabcf 0x0>; }; But then the .dts file becomes an unreadable matrix unless we have a preprocessor.. Regards, Tony