[PATCH] Implements new features for updating existing device tree nodes.

[Grant Likely]

On Sat, Oct 16, 2010 at 06:45:47AM -0700, John Bonesio wrote:
> On Sat, 2010-10-16 at 02:10 -0600, Grant Likely wrote:
> > On Sat, Oct 16, 2010 at 05:47:44PM +1100, David Gibson wrote:
> > > On Fri, Oct 15, 2010 at 08:21:17PM -0700, John Bonesio wrote:
> > > > Ok, so maybe I misunderstood. I thought we had decided that node
> > > > modifications would only happen at the top level, but now that I'm
> > > > looking back through your examples earlier today, and I see this isn't
> > > > true.
> > > 
> > > Um.. that part of the discussion got confusing.  I think only allowing
> > > the operations (and I still don't think the set implemented here are
> > > quite right, though they're close) at the top-level is a better idea.
> > > 
> > > Grant, is there a reason you think we need to have replacement as an
> > > option within each tree, rather than a "per-overlay-sheet" option.
> > 
> > Yes, because I need the ability to remove/replace a child of a
> > labelled node.  Not every node that needs to be manipulated will
> > necessarily have a label.
> > 
> > For example; I could have a labelled spi bus node with child nodes for
> > each of the spi devices.  I want to be able to remove/replace the
> > child nodes without having to label them first.
> > 
> > g.
> > 
> 
> Why not just add the label to the node you need first?

That may not be possible and/or desirable.  For instance, when the
tree is extracted from /proc.  Or if the base tree in stored in the
kernel source and an external tool is modifying it for a specific
purpose (when unable to patch the kernel tree).  Or for generated
device trees from the Xilinx toolchain for FPGAs.  Modifying the
source data isn't always an option.

Plus I want the ability to logically group related changes.  ie.
delete a device and add a device to the same bus at the same time.  Or
delete a phy node, add a replacement phy node at a different address,
and update the ethernet phy-device phandle in the same block.

g.