On Thu, Aug 04, 2011 at 06:07:15PM -0500, Matt Sealey wrote:

If you think the solution is not so great due to the complexity of
describing the IOMUX settings, including the pad definitions as binary
blobs or so such that Linux can read them out, please feel free to
take the hint and go nag the U-Boot developers at Linaro to go put
this in the right place - in U-Boot. The device tree is absolutely not
the place to define pin multiplexing settings for later parsing and
configuration by the Kernel. They should have been set up correctly
already, and they should not be being *changed* based on an arbitrary
configuration file. Consider that the i2c pin definitions you used in
your example *absolutely will not change* for the lifetime of the
board, and in most cases, will have been set up by U-Boot anyway.
There is no point telling Linux to copy in identical settings again.
What's missing from U-Boot and set up by Linux, should be moved out of
Linux back into U-Boot.

System on module vendors have quite a different point of view here.
On these systems the functionality of a pin differs depending on the
baseboard they are attached to. Still you want to be able to use the
same bootloader for all usecases. Putting the pinmux into the bootloader
would mean that each user of these systems has to flash and maintain
a custom bootloader.

Sascha

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