Support for the RV770 chipsets has now been added to the GIT master branch of xf86-video-radeonhd at freedesktop.org. So far this support has only been available in the AtomBIOS branch. Now some investigations have unveiled that the display engine blocks have not changed since RV620/RV635. Therefore AtomBIOS is not a strikt prerequisite to get the latest AMD/ATI hardware to work. Some bits to get RV770 to work have been cherry picked from the 'atombios-support' branch. These involved mainly memory controller register programming and some small fixes to the I2C code. Thus it was possible to provide support for this new hardware generation without having to wait for the AtomBIOS support branch to be ready for merging into the master branch. Some word on the atombios_support branch: Most of the work on that branch has been finished so that this branch will be merged into master after some further testing and once some cleanup has taken place. We have been asked to provide AtomBIOS support for the RadeonHD driver to speed up the driver bring up for future generations of graphics hardware. It relieves ATI of the burden to have register specification available at the time of release of new graphics hardware and thus allow it to focus on the publication of documentation for 3D programming.
Have a nice weekend :)