linux-kernel - Re: [PATCH 2/2] ARM: OMAP2+: Enable pinctrl dummy states

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Date:	Tue, 11 Sep 2012 14:15:40 -0400
From:	Matt Porter <mporter@...com>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Linux OMAP List <linux-omap@...r.kernel.org>,
	Linux SPI Devel List 
	<spi-devel-general@...ts.sourceforge.net>,
	Grant Likely <grant.likely@...retlab.ca>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
	AnilKumar <anilkumar@...com>
Subject: Re: [PATCH 2/2] ARM: OMAP2+: Enable pinctrl dummy states

On Tue, Sep 11, 2012 at 11:03:06AM -0700, Tony Lindgren wrote:
> * Matt Porter <mporter@...com> [120911 10:46]:
> > Enable pinctrl dummy states for all OMAP platforms. This allows
> > drivers to be converted to pinctrl while still running on
> > platforms that do not provide pinctrl data.
> > 
> > Signed-off-by: Matt Porter <mporter@...com>
> > ---
> >  arch/arm/mach-omap2/devices.c |    4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/arm/mach-omap2/devices.c b/arch/arm/mach-omap2/devices.c
> > index c00c689..577cd04 100644
> > --- a/arch/arm/mach-omap2/devices.c
> > +++ b/arch/arm/mach-omap2/devices.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/err.h>
> >  #include <linux/slab.h>
> >  #include <linux/of.h>
> > +#include <linux/pinctrl/machine.h>
> >  #include <linux/platform_data/omap4-keypad.h>
> >  
> >  #include <mach/hardware.h>
> > @@ -631,6 +632,9 @@ static inline void omap_init_vout(void) {}
> >  
> >  static int __init omap2_init_devices(void)
> >  {
> > +	/* Enable dummy states for those platforms without pinctrl support */
> > +	pinctrl_provide_dummies();
> > +
> >  	/*
> >  	 * please keep these calls, and their implementations above,
> >  	 * in alphabetical order so they're easier to sort through.
> 
> Hmm I think this may need to be board specific. And may need to
> be board specific and depend on unpopulated device tree?

If I run this on AM33xx with dummy states enabled, I'm able to override
that dummy state just fine with an appropriate pinctl/pinmux entry in my
DT data for spi.

Meanwhile on xM booting from board-omap3evm.c/!DT and debug enabled I
get the following:

[    1.837829] omap2_mcspi omap2_mcspi.1: no of_node; not parsing
pinctrl DT
[    1.845214] omap2_mcspi omap2_mcspi.1: using pinctrl dummy state
(default)
[    1.854278] omap2_mcspi omap2_mcspi.2: no of_node; not parsing
pinctrl DT
[    1.861572] omap2_mcspi omap2_mcspi.2: using pinctrl dummy state
(default)
[    1.870025] omap2_mcspi omap2_mcspi.3: no of_node; not parsing
pinctrl DT
[    1.877288] omap2_mcspi omap2_mcspi.3: using pinctrl dummy state
(default)
[    1.885681] omap2_mcspi omap2_mcspi.4: no of_node; not parsing
pinctrl DT
[    1.892913] omap2_mcspi omap2_mcspi.4: using pinctrl dummy state
(default)

which seems to cover things being informative enough about what is
going on. Are you wanting to see an explicit warning that the pinctrl
dummy state is in use when pinctrl data is not available?
 
> For board-generic.c we always want to see the warnings. And some boards
> insist on doing all the muxing only in the bootloader.

Which warnings are you saying we should see in the board-generic.c
case?  Sure, there's plenty of cases where this will be unused due to
somebody setting all the muxes in the bootloader and then not using
pinctrl data. I'll have to doublecheck but I believe that case is also
fine as the -single driver can't override the dummy state if the DT has
no pinctrl data for the spi driver.

-Matt
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