Messages in this thread | | | Date | Mon, 29 Nov 2010 13:07:20 -0600 | From | Scott Wood <> | Subject | Re: [PATCH 03/11] x86/dtb: Add a device tree for CE4100 |
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On Mon, 29 Nov 2010 09:53:29 +1100 Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote: > On Sun, 2010-11-28 at 17:04 +0100, Sebastian Andrzej Siewior wrote: > > >> + isa@legacy {
What is "@legacy"? I don't think I've seen that in a unit address before, googling only turns up this device tree, and a quick grep through the ISA and base OF specs turns up nothing.
> > >> + device_type = "isa"; > > >> + compatible = "simple-bus"; > > > > > >What does "simple-bus" means ? > > I added simple bus in order to get probed. But I now I rember that this > > is also supported per device_type. I get rid of it. > > device_type is a nasty bugger, we are trying to get rid of Linux > reliance on it. > > Things like "simple-bus" don't rock my boat either, it's adding to the > device-tree "informations" that are specific to the way Linux will > interpret it, which is not how it should be.
The motivation for simple-bus comes from Linux, but its definition is OS-neutral. It indicates that no special bus knowledge is required to access the devices under it.
I don't think it applies to ISA, though -- I/O space is special bus knowledge, and the "ranges" looks weird for memory-space as well.
If we're going to get rid of device_type here, it would be nice to have some other way to indicate that this node follows the ISA binding, without having to recognize an implementation-specific compatible.
-Scott
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