On Tue, Nov 26, 2024 at 02:36:32PM +1100, Michael Ellerman wrote: > Michael Ellerman <mpe@xxxxxxxxxxxxxx> writes: > > "Rob Herring (Arm)" <robh@xxxxxxxxxx> writes: > >> While OpenFirmware originally allowed walking parent nodes and default > >> root values for #address-cells and #size-cells, FDT has long required > >> explicit values. It's been a warning in dtc for the root node since the > >> beginning (2005) and for any parent node since 2007. Of course, not all > >> FDT uses dtc, but that should be the majority by far. The various > >> extracted OF devicetrees I have dating back to the 1990s (various > >> PowerMac, OLPC, PASemi Nemo) all have explicit root node properties. > > > > I have various old device trees that have been given to me over the > > years, and as far as I can tell they all have these properties (some of > > them are partial trees so it's hard to be 100% sure). > > > > So LGTM. > > Turns out I was wrong. > > The warning about #size-cells hits on some powermacs, possible fixup > patch here: > > https://lore.kernel.org/linuxppc-dev/20241126025710.591683-1-mpe@xxxxxxxxxxxxxx/ The Open Firmware specification is extremely clear that a "missing" "#size-cells" property means this bus has the default value of 1. https://www.openfirmware.info/data/docs/of1275.pdf (page 186). DTC or FDT might want to do things differently, but expecting decades older stuff to conform to its ill-conceived unnecessarily super wordy stuff is, well, not a plan that is likely to work very well :-) Segher
