Hi Rob,
Thanks for your feedback.
On 2025-07-02 08:33:10 -0500, Rob Herring wrote:
> On Wed, Jul 2, 2025 at 3:50 AM Niklas Söderlund
> <niklas.soderlund+renesas@xxxxxxxxxxxx> 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>
> > };
> > };
> > };
> >
> > The false warnings, and especially the confusion on why it only triggers
> > for single endpoints where the address is 0, leads to confused user and
> > reports of issues with DTS files. To try and mitigate this behavior by
> > demote the check to W=2 and document the possibility for false warnings
> > in the check itself.
> >
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> > ---
> > Hi,
> >
> > This solution was lightly hinted at [1] by Rob and I have ran with it
> > for a while locally and I'm happy with the result. Lets see what the
> > rest of you think.
> >
> > 1. https://lore.kernel.org/all/20250109150327.GA3352888-robh@xxxxxxxxxx/
> > ---
> > scripts/Makefile.dtbs | 6 +++---
> > scripts/dtc/checks.c | 5 +++++
>
> dtc changes have to go upstream first. I can drop this when applying.
Ohh I see now there is a separate tree for dtc. If you agree with the
direction of this work I can submit a patch for this to
devicetree-compiler@xxxxxxxxxxxxxxx. Sorry for not realizing this.
If you like please drop this when applying, and please drop the last
half paragraph from the commit message "and document the possibility for
false warnings in the check itself".
>
> Rob
--
Kind Regards,
Niklas Söderlund
