[RFC PATCH v3 2/5] pinctrl: add dt binding support for pinmux mappings

[Dong Aisheng-B29396]

> -----Original Message-----
> From: Shawn Guo [mailto:shawn.guo at linaro.org]
> Sent: Thursday, January 12, 2012 12:04 PM
> To: Stephen Warren
> Cc: Richard Zhao; linus.walleij at stericsson.com; s.hauer at pengutronix.de; linux-
> kernel at vger.kernel.org; rob.herring at calxeda.com; kernel at pengutronix.de; Simon
> Glass (sjg at chromium.org); cjb at laptop.org; Dong Aisheng-B29396; devicetree-
> discuss at lists.ozlabs.org; linux-arm-kernel at lists.infradead.org; Dong Aisheng
> Subject: Re: [RFC PATCH v3 2/5] pinctrl: add dt binding support for pinmux
> mappings
> Importance: High
> 
> On Wed, Jan 11, 2012 at 03:59:26PM -0800, Stephen Warren wrote:
> > Shawn Guo wrote at Wednesday, January 11, 2012 4:57 PM:
> > > This is somehow overkilled to me.  Doing this will create a big
> > > mount of .dtsi files to bloat folder arch/arm/boot/dts.  Putting the
> > > 'combinations' in <soc>.dtsi seems perfect fine to me.
> >
> > I see a couple problems with that approach:
> >
> > 1) <soc>.dtsi gets very bloated,
> 
> In theory, it's possible.  But in the real world, I do not think this will be an
> issue.  From the experience from working on previous imx platforms, the mux
> chosen on Freescale reference design board will likely be reused on custom
> boards much.
> 
I'm don't think it's a big issue.
If we really find it getting very bloated, we will refine it later.

> > and wastes space containing board-
> > specific data for boards other than the "current" one.
> 
> Technically, it's not the board specific data, because what pins can be put
> together consisting of a function is really soc specific.
> 
Yes, it's true.

> >
> > 2) We need to invent some more complex DT format so you can reference
> > these canned combinations from the device drivers, rather than simply
> > enumerating the mux value for each pin/group.
> 
> Sorry, I do not get that.
> 
> Regards,
> Shawn
> 
> >
> > You could put the combination .dtsi files in arch/arm/boot/dts/<soc>
> > to maintain some extra order.