Subject: Re: [PATCH 2/6] PowerPC 440EPx: Sequoia DTS

From: Segher Boessenkool <[email-masked]>
Date: Tue, 7 Aug 2007 19:01:01 +0200

>> It would be possible, I guess, to define a 'swizzled-ranges' property
>> or something which allows child devices to be embedded in the parent's
>> address range in a not-direct way.  However, the swizzling on the
>> flash bank is really a property of the flash bank, not of the parent
>> bus - requiring it to be encoded in the parent is pretty yucky -
>> especially if the flash bank is just part of a larger chunk of bus
>> address space, defined by a single large ranges entry in the parent.
>
> It's more a property of the connection between the bus and the flash
> chips, and that connection could be described as its own "bus" node,
> something like:

But it's not a bus in reality.  There is no need to introduce
a fake bus here, it won't help anything AFAICS.

> Similar intermediary buses could be used for flashes with indirect
> access (SPI and such).

There are perfectly good mechanisms already for describing
those, too (you make a device node for the controller, and
it defines its own address space).

Segher