Re: ARM ecosystem drivers, they are a nightmare.
"Nightmare" wasn't my experience when writing my first ever Linux driver (I'd done others before) for a MontaVista-on-ARM box to talk to a high performance serial chip *raw*, without going through all the bells and whistles and overhead of the tty driver stack.
In fact when the IT department insisted that only Dell kit was persmissible, we found the same serial chip on a PCI card, and recompiled the driver (under Suse rather than MontaVista), and the IT department were happy, till they noticed it wasn't Windows, therefore still wasn't permissible on *their* network. But that's another story.
I was impressed, even if others might not have been.