On 26-Oct-23 01:01, Rob Herring wrote: > On Fri, Oct 13, 2023 at 02:24:24PM +0530, Aradhya Bhatia wrote: >> Exempt 'ports' from the rule which asserts that nodes with single child >> node having reg = 0, should not have the '#size-cells' and >> '#address-cells' properties. >> >> Ports of certain hardware do need to be described as only having a >> single child node 'port@0', especially when hardware has multiple ports, >> and the other ports 'port@x' are planned to be added subsequently. In >> such cases, just using 'port', would be an inaccurate hardware >> description. >> >> For example, Texas Instruments' DSS (display-subsystem), which has 2 or >> 4 video ports depending on the SoC. Describing the first video port with >> just 'port' under ports would be inaccurate and even slightly >> misleading. Simply using port@0 (when other ports are not added) >> produces the following warning, while making dtbs with W=1 flag set[0]. > > There's a reason this is behind W=1. > > In general, if you only have a single 'port' it should be just 'port' > which is equivalent to port 0. There's exceptions to that, so the > warning is off by default. Thank you for reviewing the patch, Rob! I had a discussion offline, and I agree that the patch may not be needed after all. Moreover, upon looking at the tests provided in upstream dtc tree, I also realized that the check is exclusively limited to port@0, and does not include any random 'child@0'. This makes the patch make a lot less sense too. Regards Aradhya > >> code-block :: >> >> Warning (graph_child_address): /bus@100000/dss@4a00000/ports: >> graph node has single child node 'port@0', >> #address-cells/#size-cells are not necessary >> >> Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx> >> >> [0]: https://lore.kernel.org/all/570903b6-8239-d44a-5fac-71700804cb5d@xxxxxx/ >> --- >> scripts/dtc/checks.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) > > This is a copy of upstream dtc. We don't take patches for it (except in > emergency). Look at the commit history. > > Rob
