* Simon Glass <s...@chromium.org> [120127 07:12]:
>
> On Thu, Jan 26, 2012 at 6:21 PM, Tony Lindgren <t...@atomide.com> wrote:
> >
> > Maybe we need two bindings: A minimal subset of what Stephen is suggesting
> > that can handle 95% of the muxes with minimal overhead, then what you're
> > suggesting for the few muxes that need multiple states?
>
> Perhaps that would work, it certainly deals nicely with making the
> rare cases less ugly if indeed they are rare. Of course a single
> binding that is not too ugly and still reasonably efficient would be
> best.
>
> I will have a think about this a bit more and see if anything leaps
> out. It's quite an interesting problem...
Just to try to recap what has come up so far:
1. We need to avoid bloating things for basic cases to initialize
several hundred pins.
2. Some muxes need to define multiple states.
3. We need to pass a flag for each mux to know whether or
not it can be freed after init.
So how about let's do separate static and dynamic bindings,
something like this:
/*
* Static init time only mux where
* we only specify phandle to driver
* and, offset of the mux, and the value.
* These pins are discarded after init.
*
* Format: mux_ctrl offset value
*/
pinctrl-static = <&pmx_driver1 0x0020 0x1245
&pmx_driver2 0x0022 0x6578>;
/*
* Dynamic mux where the mux is kept around after
* init and multiple states can be defined for
* a mux as a subnode of the pinmux controller.
*
* Format: mux_phandle initial state
*/
pinctrl-dynamic = <&pmx_sdhci PMX_STATE_ENABLED
&pmx_ehci_xcv PMX_STATE_ENABLED>;
This would make pinctrl-static binding follow the same
standard as GPIO binding and can be parsed easily with
of_parse_phandle_with_args.
Then for pinctrl-dynamic we can make a custom parser,
and the binding can follow the more readable format as
Simon posted.
Regards,
Tony
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