From: Grant Likely <grant.likely@secretlab.ca>
To: Tony Lindgren <tony@atomide.com>
Cc: Shawn Guo <shawn.guo@linaro.org>,
"linus.walleij@stericsson.com" <linus.walleij@stericsson.com>,
"devicetree-discuss@lists.ozlabs.org"
<devicetree-discuss@lists.ozlabs.org>,
"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"rob.herring@calxeda.com" <rob.herring@calxeda.com>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
"cjb@laptop.org" <cjb@laptop.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Dong Aisheng <dongas86@gmail.com>
Subject: Re: Pinmux bindings proposal
Date: Wed, 18 Jan 2012 13:20:57 -0700 [thread overview]
Message-ID: <20120118202057.GH4223@ponder.secretlab.ca> (raw)
In-Reply-To: <20120118153256.GB22818@atomide.com>
On Wed, Jan 18, 2012 at 07:32:56AM -0800, Tony Lindgren wrote:
> * 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..
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.
next prev parent reply other threads:[~2012-01-18 20:21 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-13 20:39 Pinmux bindings proposal Stephen Warren
2012-01-14 7:09 ` Shawn Guo
2012-01-17 18:47 ` Stephen Warren
2012-01-18 3:32 ` Shawn Guo
2012-01-18 19:00 ` Stephen Warren
2012-01-16 12:50 ` Dong Aisheng-B29396
2012-01-17 8:23 ` Shawn Guo
2012-01-17 9:46 ` Dong Aisheng-B29396
2012-01-17 14:13 ` Shawn Guo
2012-01-17 19:32 ` Stephen Warren
2012-01-18 3:44 ` Dong Aisheng-B29396
2012-01-18 4:47 ` Shawn Guo
2012-01-18 19:24 ` Stephen Warren
2012-01-17 19:28 ` Stephen Warren
2012-01-18 11:06 ` Dong Aisheng-B29396
2012-01-20 20:28 ` Stephen Warren
2012-01-27 12:00 ` Linus Walleij
2012-01-27 16:58 ` Stephen Warren
2012-01-17 19:21 ` Stephen Warren
2012-01-18 4:01 ` Shawn Guo
2012-01-18 9:32 ` Dong Aisheng-B29396
2012-01-17 19:09 ` Stephen Warren
2012-01-18 7:24 ` Dong Aisheng-B29396
2012-01-18 19:42 ` Stephen Warren
2012-01-16 18:28 ` Grant Likely
2012-01-18 14:13 ` Tony Lindgren
2012-01-18 14:30 ` Shawn Guo
2012-01-18 15:32 ` Tony Lindgren
2012-01-18 16:29 ` Tony Lindgren
2012-01-18 20:22 ` Grant Likely
2012-01-18 20:20 ` Grant Likely [this message]
2012-01-19 10:31 ` Tony Lindgren
2012-01-18 20:02 ` Stephen Warren
2012-01-19 10:57 ` Tony Lindgren
2012-01-20 20:50 ` Stephen Warren
2012-01-23 20:13 ` Tony Lindgren
2012-01-23 22:54 ` Stephen Warren
2012-01-27 13:11 ` Linus Walleij
2012-01-18 12:16 ` Thomas Abraham
2012-01-18 19:52 ` Stephen Warren
2012-01-19 17:01 ` Tony Lindgren
2012-01-19 13:10 ` Thomas Abraham
2012-01-19 16:56 ` Tony Lindgren
2012-01-19 17:38 ` Thomas Abraham
2012-01-19 18:20 ` Tony Lindgren
2012-01-19 18:38 ` Thomas Abraham
2012-01-20 10:05 ` Tony Lindgren
2012-01-20 16:17 ` Thomas Abraham
2012-01-20 17:53 ` Tony Lindgren
2012-01-21 1:38 ` Thomas Abraham
2012-01-20 21:15 ` Stephen Warren
2012-01-20 21:11 ` Stephen Warren
2012-01-21 1:27 ` Thomas Abraham
2012-01-23 22:43 ` Stephen Warren
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