Re: [PATCH] of: support an enumerated-bus compatible value

[Segher Boessenkool <segher-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>]

>> Why would you want to instantiate devices that you cannot address
>> at all anyway?  The only driver that can know what to do with the
>> device node is the driver for the device that has the phandle
>> reference to it; it can instantiate it.
>
> It's not a single device referencing it, it's multiple devices
> referencing it, and we can do useful things even with no external
> references at all.  The node itself is a real thing that we can  
> point at
> and control (using GPIOs or something similar).

So you *can* address the device, you just don't want to show that
in the device tree (I don't blame you, it's quite impossible to
design a sane addressing scheme for this, all this stuff is so
ad-hoc).  I see.  You could make it the kid of a GPIO controller
node, but then what if it is controlled by two (or more!) GPIO
controllers?

There is still no reason for the fake bus node to have a "compatible"
property though.  What could it possibly mean?  "This bus does not
exist at all but you access it in bla bla bla way"?  That just doesn't
make sense.  It doesn't exist, you do not access it, it has no
programming model, it has no "compatible" property.


Segher