From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Likely Subject: Re: Pinmux bindings proposal Date: Wed, 18 Jan 2012 13:22:19 -0700 Message-ID: <20120118202219.GI4223@ponder.secretlab.ca> References: <74CDBE0F657A3D45AFBB94109FB122FF17801D202F@HQMAIL01.nvidia.com> <20120116182808.GG4223@ponder.secretlab.ca> <20120118141329.GA22818@atomide.com> <20120118153256.GB22818@atomide.com> <20120118162943.GC22818@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: <20120118162943.GC22818-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Tony Lindgren Cc: "cjb-2X9k7bc8m7Mdnm+yROfE0A@public.gmane.org" , "linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org" , "kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org" , "s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , Dong Aisheng List-Id: devicetree@vger.kernel.org On Wed, Jan 18, 2012 at 08:29:43AM -0800, Tony Lindgren wrote: > * Tony Lindgren [120118 07:00]: > > * 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: > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 pinmux =3D > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 <"default" &pmx_= sdhci_active> > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 <"suspend" &pmx_= sdhci_suspend>; > > > >> > > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* 1:n example: */ > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 pinmux =3D > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 <"default" &pmx_= sdhci_mux_a> > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 <"default" &pmx_= sdhci_pincfg_a> > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 <"suspend" &pmx_= sdhci_mux_a> > > > >> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 <"suspend" &pmx_= sdhci_pincfg_a_suspend>; > > > >> > > > >> > > > >> Yeah, don't do this. =A0Mixing phandle, string and cell values in a > > > >> property gets messy and could become troublesome to parse. =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 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 =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.. > = > Forgot to mention that as long as we all standardize to use something > common for #pin-args and of_parse_phandle_with_args(), the pin mapping > could depend on the pinmux driver for selecting whether or not to use > a phandle for each pin. Yes, the actual layout parsing should remain in the control of the pinmux controller like it does for irqs, gpios, etc. g.