Could you try building the driver without patch 104 (comment it out from debian/patches/series, then run 'dpkg-buildpackage -b', and if needed, 'apt-get build-dep xserver-xorg-video-ati' before that)?
Could you try building the driver without patch 104 (comment it out from debian/ patches/ series, then run 'dpkg-buildpackage -b', and if needed, 'apt-get build-dep xserver- xorg-video- ati' before that)?