On Wed, May 11, 2016 at 09:02:39AM +0200, Thomas Huth wrote:
> On 10.05.2016 19:32, Andrew Jones wrote:
> > Search up the tree until we find #address-cells/#size-cells.
> > Also only assign outputs if both address and size are found.
> >
> > Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
> > ---
> > lib/devicetree.c | 17 +++++++++++++----
> > lib/devicetree.h | 3 ++-
> > 2 files changed, 15 insertions(+), 5 deletions(-)
> >
> > diff --git a/lib/devicetree.c b/lib/devicetree.c
> > index a5c7f7c69ddfd..d3751e2b7e7f9 100644
> > --- a/lib/devicetree.c
> > +++ b/lib/devicetree.c
> > @@ -24,21 +24,30 @@ int dt_get_nr_cells(int fdtnode, u32 *nr_address_cells, u32 *nr_size_cells)
> > {
> > const struct fdt_property *prop;
> > u32 *nr_cells;
> > - int len;
> > + int len, nac, nsc;
> > +
> > + while (1) {
> > + prop = fdt_get_property(fdt, fdtnode, "#address-cells", &len);
> > + if (prop != NULL || len != -FDT_ERR_NOTFOUND)
> > + break;
> > + fdtnode = fdt_parent_offset(fdt, fdtnode);
> > + }
>
> Why do you need this search? ePAPR clearly states:
>
> "The #address-cells and #size-cells properties are not inherited from
> ancestors in the device tree. They shall be explicitly defined."
You are right.
My skimming of Documentation/devicetree/booting-without-of.txt was
sloppy and I missed basically the same quote
"Note that the parent's parent definitions of #address-cells and
#size-cells are not inherited so every node with children must
specify them."
>
> So as far as I can see, it should always be enough to look up the
> properties in the parent of the node, no need for a recursion here?
So, yes, I should look in the current node, and then the parent, and
then just assert.
Thanks,
drew
>
> Thomas
>
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