Re: [PATCH v3 07/15] devicetree: Add DeviceTree live tree representation

[David Gibson]

On Fri, Nov 06, 2026 at 06:43:18PM -0800, Doug Anderson wrote:
> Hi Simon,
> 
> On Wed, Nov 4, 2026 at 6:08 AM Simon Glass <sjg@xxxxxxxxxxxx> wrote:
> >
> > Hi Doug,
> >
> > On Sun, Nov 1, 2026 at 4:02 PM Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
> > >
> > > Add `devicetree.py` providing `DeviceTree`, a non-flattened in-memory
> > > representation of a devicetree node and its subtree:
> >
> > Please can you start with the motivation, i.e. why a live tree is
> > needed and what will use it? The list below mostly repeats the
> > docstrings.
> 
> Makes sense. In my draft v4 I've updated the commit message to lead
> with the motivation and condensed the summary so it doesn't repeat the
> docstrings:
> 
>     `pylibfdt`'s `Fdt` and `FdtRo` classes operate directly on flattened
>     device tree blobs, where inserting or deleting nodes and properties
>     shifts subsequent node offsets. That works well for in-place queries and
>     localized edits, but makes multi-tree comparison, structural diffing,
>     and bottom-up tree construction (as needed by the upcoming `fdtfactor`
>     tool) awkward and error-prone.
> 
>     Add `pylibfdt/devicetree.py` providing `DeviceTree`, an in-memory live
>     tree representation where each node holds `props` (a dict mapping
>     property name to `libfdt.Property`) and `children` (a dict mapping child
>     node name to child `DeviceTree`), along with `unflatten()` and
>     `flatten()` to convert between `FdtRo`/`Fdt` blobs and live trees, and
>     helpers for path lookup, node creation, and pre-order traversal.
> 
>     Add unit tests in `tests/devicetree_tests.py` covering `DeviceTree`
>     round-tripping, subtree unflattening, duplicate-name and corrupt-tree
>     rejection, and navigation helpers.
> 
> > > diff --git a/devicetree.py b/devicetree.py
> > > new file mode 100644
> > > index 0000000..f81b8fc
> > > --- /dev/null
> > > +++ b/devicetree.py
> > > @@ -0,0 +1,226 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
> > > +"""devicetree - Non-flattened in-memory device tree representation in Python."""
> >
> > I'd forgotten about this but PyPI has Zephyr's python-devicetree
> > [1][2], which installs a top-level 'devicetree' package.
> >
> > I'm not sure what to suggest. Would libfdt_devicetree be too awful?
> 
> Right. I'm OK with libfdt_devicetree. David: do you have any
> objections?

Don't love it, but can't quickly think of a better option.

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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