https://bugs.freedesktop.org/show_bug.cgi?id=84500
--- Comment #21 from Alexandre Demers alexandre.f.demers@gmail.com --- (In reply to John Bridgman from comment #20)
Yes, AFAIK HD 78xx is Pitcairn and HD 79xx is Tahiti.
Well, I'm sick (literally) and I mixed José's dmesg with mine. Everything is fine with the device ID then.