On Tue, Jul 8, 2025 at 2:52 AM Niklas Söderlund
<niklas.soderlund+renesas@xxxxxxxxxxxx> wrote:
>
> Hi David,
>
> Thanks for your comments.
>
> On 2025-07-08 13:07:12 +1000, David Gibson wrote:
> > On Sun, Jul 06, 2025 at 02:26:38PM +0200, Niklas Söderlund wrote:
> > > The dtc graph_child_address check can't distinguish between bindings
> > > where there can only be a single endpoint, and cases where there can be
> > > multiple endpoints.
> > >
> > > In cases where the bindings allow for multiple endpoints but only one is
> > > described false warnings about unnecessary #address-cells/#size-cells
> > > can be generated, but only if the endpoint described have an address of
> > > 0 (A), for single endpoints with a non-zero address (B) no warnings are
> > > generated.
> > >
> > > A)
> > > ports {
> > > #address-cells = <1>;
> > > #size-cells = <0>;
> > >
> > > port@0 {
> > > #address-cells = <1>;
> > > #size-cells = <0>;
> > >
> > > sourceA: endpoint@0 {
> > > reg = <0>
> > > };
> > > };
> > > };
> > >
> > > B)
> > > ports {
> > > #address-cells = <1>;
> > > #size-cells = <0>;
> > >
> > > port@0 {
> > > #address-cells = <1>;
> > > #size-cells = <0>;
> > >
> > > sourceB: endpoint@1 {
> > > reg = <1>
> > > };
> > > };
> > > };
> > >
> > > Add a comment in the check to document this.
> >
> > Hm. I don't know the graph bindings at all well, so I'll take your
> > word for it on what's happening here. But simply documenting this
> > within the code doesn't seem particularly useful. Someone running dtc
> > will still see the bogus error, and they'd have a pretty long way to
> > go to find this explanation.
>
> It would have been useful for me, I spent a lot of time questioning
> myself on why my dts files produced warnings and where incorrect. I even
> submitted patches to try and work around this issue before learning
> these where false positives. A comment here would have saved me that
> work :-)
>
> I think if the check stays the comment bring some value.
>
> >
> > Probably better to simply remove the check (and maybe comment that it
> > would be nice to check further, but we can't adequately it from a
> > valid case).
>
> I'm OK with removing the check too. This comment was first posted
> together with a change to demote this check to W=2 (instead of W=1) that
> have now been posted separately [1]. I will wait for feedback on that
> and let smarter people then me pick the best way forward.
I'm okay with removing it. It's somewhat redundant now with the schemas.
Another option though would be making it default off.
Rob
