On Tue, Sep 6, 2022, at 19:35, Rob Herring wrote: > On Wed, Sep 07, 2022 at 02:00:53AM +0900, Hector Martin wrote: >> On 07/09/2022 01.10, Rob Herring wrote: >> >> So at this point, I think it would make sense if I post a v2 with all >> >> the updates so far (sorry, given the long drawn out discussions on >> >> this, I've lost track of what changes have been made to the code, so >> >> I won't include a detailed change log.) >> > >> > As I said elsewhere, sub-nodes is probably the right choice here. I >> > think they need compatible strings in the child nodes, and addressing >> > has to be sorted out which it seems may also break OpenBSD. >> >> So addressing only makes sense for GPIO, out of the nodes we have so far >> - that's the only thing with two discrete instances whose access can be >> entirely described by a single base key name, and which are otherwise >> compatible. >> >> Everything else is pretty much single-instance, and talks to multiple >> keys, so there isn't one single "address" key that would make semantic >> sense to use as the node address. > > Unit-addresses are just the first address in 'reg'. So multiple > addresses or not doesn't really matter. > >> There are some indexed keys, but at a >> deeper level (e.g. multiple battery cells part of the charge control >> subsystem, multiple Type C ports as part of the AC/power input >> subsystem, etc.). And in those cases, these subdevices are mostly >> homogeneous and we would never need multiple nodes for them at the DT >> level, they'd just be implicitly handled by those drivers. > > Type-C will be fun depending on how much of the muxing/altmode > details have to get exposed. Type-C is going to be a lot of "fun", but the SMC is not directly involved. I still don't have a full picture but these boards have TPS6598x chips which trigger the entire mess whenever a new mode was negotiated and the "Apple Type-C PHY" contains the actual mux. The SMC has a side channel to these TPS6598x chips as well but it seems to only handle charging without having to communicate with whatever kernel is running on the main processor. Sven
