Last progress:

I edited a HUB table to support protocol version 2 (my hub has this protocol version !) and kernel now recognizes it, enumerates it and command 'lsusb' shows it ! (All of it - for self-powered hub, of course).

But next stop is - "ignoring external hub". It needs some analysis - why it is chosen to ignore... Besides of that there is a lot of debug output which requires some analysis too.

EDIT: It looks like I discovered the reason of unstable results - my USB female-2-female connector has preference which side to connect to N900 (!?)