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SubjectRe: [PATCH 2/2] ARM: OMAP2+: Enable pinctrl dummy states
Added Linus Walleij to Cc as well.

* Matt Porter <mporter@ti.com> [120911 11:24]:
> On Tue, Sep 11, 2012 at 11:03:06AM -0700, Tony Lindgren wrote:
> > * Matt Porter <mporter@ti.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@ti.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.

But do you get an error then if the desired pins are not found?
If you do get an error, then sounds like it's OK to do.

> 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?

Well I think we should consider at least the following:

1. Always see warnings when device tree is populated with board-generic.
If somebody wants to use bootloader only muxing with DT, they can patch
in pinctrl_provide_dummies() somewhere. But let's assume we always
want to see the warnings with board-generic.c and DT.

2. For legacy booting without DT, we should not see any warnings
from pinctrl-single.c as it's DT based.

3. There may be other non-pinctrl drivers too that are not DT
based, and in those cases we should see the warnings as well
for in the non-DT case.

> > 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.

Yeah I guess it's the case #1 above for board-generic.c.

Regards,

Tony


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