Hi Frank,

On Jul 5, 2016, at 17:24 , Frank Rowand [off-list ref] wrote:

On 07/05/16 01:31, Mark Brown wrote:

quoted

On Mon, Jul 04, 2016 at 01:58:53PM -0700, Frank Rowand wrote:

quoted

On the other hand, I have no previous detailed knowledge of the beagle
family.

This is in no way specific to the BeagleBones, there's plenty of other
boards out there with similar setups like the Raspberry Pi and its
derivatives.

Yes, absolutely.  I'm just picking on the beaglebones because that is
what Pantelis has recently used for examples.  (He has mentioned other
connector types and expansion boards in his presentations.)

And we need to think beyond beaglebone, pi, arduino, and grove 
type of connectors.

Some other connectors that are obvious are pci and possibly usb.

Yes, in fact a growing number of platforms come with discoverable
PCI/USB boards which provide the busses and interfaces that
non-discoverable boards are plugged in.

Think an i2c-bus on pci-e boards on which a number of I2C peripherals
are located. The Vendor/Product IDs are the same for all these
expansions boards since the h/w designers do not want to spend money
on even a dip-switch or EEPROM for the IDs.

quoted

quoted

   - for bones with the same pinout:
     - the pins are routed to different function blocks on the
       SOC because different bones may have different SOCs?
       - the different functional blocks are compatible or not?

This is the general case, there will be a substantial level of
compatibility between different base boards by virtue of the pinouts
being the same but obviously there will be some variation in the
specifics (and even where that exists it may not be enough to be visible
at the DT level for the most part).  That said there will doubtless be
some plug in modules that want to rely on the specifics of a given base
board rather than remain compatible with general users of the interface.

Regards

— Pantelis