[FS#83] BTHOMEHUBV5A logical switch ports don't reflect real-life physical labels

[LEDE Bugs]

The following task has a new comment added:

FS#83 - BTHOMEHUBV5A logical switch ports don't reflect real-life physical labels
User who did this - James Finnie (jimbof)

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Changing the appropriate line for HH5A in 02_network to:
"0:lan:3" "1:lan:4" "2:lan:2" "4:lan:1" "6t at eth0"
does set up the LAN ports so they are numbered correctly.

However it is also a quirk(?) of this chipset it seems that the WAN ethernet port requires a VLAN setting up on it for it to be useable once the LAN is configured as above.  Yet there appears to only be one CPU port on the switch.

So the following "kind of" works"
"0:lan:3" "1:lan:4" "2:lan:2" "4:lan:1" "5:wan:1" "6t at eth0"

I say "kind of" - because it doesn't really make much sense, but it does set up the appropriate VLANs to make the hardware work.  It seems the CPU port described above is actually serving two ethernet interfaces (eth0,eth1) - yet eth1 isn't represented anywhere by the above line; this has the knock-on of having to manually enter the eth1.2 VLAN in LUCI to get WAN working, instead of being able to click the appropriate radio button.  

Is this really how the hardware works?  Most other designs with two interfaces on one switch like this seems to have two CPU ports - one for each eth interface.  Lantiq's diagram in their product information seems to show two lines from the switch to the CPU, kind of implying there are two CPU ports.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=83#comment308