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

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 07/03/2012 09:43 AM, Segher Boessenkool wrote:
>>> 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.
>>
>> Well, as everyone keeps saying this seems to be a limitation of the
>> current device tree rather than something that's actually sensible in
>> and of itself.
> 
> But that is my point: it is *not* a limitation of the device tree,
> the device tree can describe the hardware just fine without doing
> some weird "compatible" property.  The limitation is in the current
> Linux kernel code; _it_ should be fixed, don't add decorations to
> the device tree to work around shortcomings in a single OS.  The
> device tree describes the structure of the hardware, not the structure
> of the device model in the OS.

No, it's definitely a DT limitation.

DT assume that everything is addressable and hence you have to structure
it as buses where all the nodes have children with addresses. That's
what the proposed DT binding is doing.

Note that addressability (there's some integer value, or list of integer
values, that identifies a device) is entirely different from usability
(the node exists and the driver for which can provide services to the
drivers for other nodes). I think that point has been lost in the last
few messages in this sub-thread.