On Tue, Jun 28, 2022 at 03:47:59PM +0200, Michael Walle wrote: > Horatiu, can we determine the actual number of ports (or maybe > determine if its a LAN9668 or a LAN9662) from the hardware itself > in an easy way? That way we wouldn't need a new compatible string, > but could use the generic "lan966x" one. Never seen a lan966x switch, but if it's anything like the Ocelot-1 family, you should be able to determine the port count by reading the out-of-reset value of any register that contains a port mask which has all ones by default (any of the PGIDs in the multicast/flooding destinations range, or the VLAN table port masks for any VLAN ID). Or you can read the size of the packet buffer and infer from that which switch model it is, based on a driver hardcoded lookup table. I fully expect a switch with fewer ports to have smaller packet buffer. See ocelot_detect_features() for an example of registers I am talking about. Maybe lan966x has something similar. Of course these are just band aids and it would still be good to modify the device trees with the proper compatible = "microchip,lan9668-switch", "microchip,lan966x-switch"; rather than rely on educated guesswork (which is still guesswork, after all).
