On Tue, Aug 9, 2011 at 10:34 AM, Grant Likely [off-list ref] wrote:

We talked about this a bit at Linaro connect. ?Outside of the more
complex runtime-reconfiguration of pin mux, there is a general need
for arbitrary initialization sequences to registers. ?Also, pretty
much exactly what you need for tegra is needed for imx, omap and many
others. ?The though was, rather than trying to come up with some kind
of pinmux-specific binding for pin states, which could end up being
very verbose if everything was split out into properties, we could
instead have a binding for register initialization sequences.
Something like this:

? ? ? ?pinmux-initseq = <reg1 value1> <reg1 value2> ...;

And then add some macros for DTC to make it easier to define things
like pinmux setup tables. ?Although the binding above is probably too
simple and naive.

This seems to break the philosophy of what the device tree should do
-- it should describe the hardware so that the driver will know how to
program it, not include the code itself?

I know it's a hairy problem to deal with one compact pinmux
representation that fits all needs. Maybe making it overly generic is
the wrong way to go about it, and let each implementation define what
it needs? That way the simpler implementations can do something
reasonably simple without having to deal with the overly complex
options of the (over?) generalized platforms out there.


-Olof