Special Tag RT3052 vs RT5350 and MT76x8

[R.W. van Schagen]

I am trying to write a DSA driver for the MT76x8 and hopefully have it compatible with the RT5350 and even the RT3052.

I can’t figure out what the difference is between the RT3052 which states for the SGC2 register (101100E4) that it is TX but RT5350 and MT7628 say TX/RX implying that I could also use the TAG to steer egress to specific port??

For having only the TAG towards the CPU port is enough DSA and use the FDB to steer egress packets. This works perfectly without VLAN membership checking on the front facing ports and have the Linux Bridge vlan unaware (vlan_filtering 0). The switch inserts the PVID with a port Tag. But as soon as I enable vlan filtering on the switch (reg 10110014 PFC1) I get filtering but loose the TAG (all show as x8100). However if I enable TX on the same port, the switch is inserting the proper Tag but this also gets transmitted out of any other port that is part of the same VLAN VID and thus doesn’t get recognised by any other device.

Can any of the Mediatek people share some insights on this problem? How do I get vlan membership checking AND the special Tag at the same time but only transmitted to the CPU port?

Thanks very much!