The patch worked for me: no more system freezes when switching VT. Please take it into account.
amd64 testing 01:05.0 VGA compatible controller [0300]: ATI Technologies Inc RS482 [Radeon Xpress 200M] [1002:5975] -- To UNSUBSCRIBE, email to debian-x-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org