Messages in this thread | | | Date | Wed, 18 Jan 2012 13:22:19 -0700 | From | Grant Likely <> | Subject | Re: Pinmux bindings proposal |
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On Wed, Jan 18, 2012 at 08:29:43AM -0800, Tony Lindgren wrote: > * Tony Lindgren <tony@atomide.com> [120118 07:00]: > > * Shawn Guo <shawn.guo@linaro.org> [120118 05:57]: > > > On 18 January 2012 22:13, Tony Lindgren <tony@atomide.com> wrote: > > > > Hi, > > > > > > > > * Grant Likely <grant.likely@secretlab.ca> [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.. > > 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.
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