I know, but when not having a suitable one for 5.1, then using one from 5.7 may be an option.
I still wonder though, why adding the reserved region helped, because it is not needed (and not present) with 5.7.
Most likely there must be some code in 5.7 skipping that region without that explicit setting in device tree.
Anyway, the point of all this has been to see if the older kernel (5.1) had the same errors as present with amlogic's 4.9 kernel:
9.2.2 DVB tbs driver / Hauppauge USB wintv dual HD / Tvheadend conflict - Hardware - CoreELEC Forums
in order to possibly find the fix in mainline to port it back to amlogic's 4.9.
Too bad the usb3 port works in 5.1 already, which seems to be the first version with some initial support for g12, so there is no opportunity to bisect the fix.