pattakosn, ask the developers that tried to get a driver written.
Word is that imgtec changes the chips even within a series from customer to customer. So e.g. you reverse engineered chip type, say, A-1 that is uses on a Vendor-X board. Now, you see that this chip is used on a Vendor-Y board. Wohoo? No. It likely won't work with chip A-1 on Vendor-Y board because something is different. Great, isn't it?
Furthermore, yes, there are surely NDAs all over the place. But since none of any of the firms hold a 100% of Imgtec they can't do much about it.
Stop TCPA, stupid software patents and corrupt politicians!