Dunno about the NVidia version.Theirs works rather differently - the GO bit is there, but there's another append register which is used to tell the controller that a new tag has been added to the CPB list.
The only thing we currently use the GO bit for is to switch between ADMA and port register mode. Could be there's something we need to do there, though, who knows..
You shouldn't ever need to touch GO other than the ADMA / legacy mode
switch as you say.
The NVIDIA ADMA hw is not based on the Pacific Digital core.