EDIT: 05/28/2011: Add card functionality as of r41792
I have recently been working on the radeon_hd graphics driver and accelerant to get extended mode setting complete for the Radeon r600-r800 chipsets (Roughly Radeon HD 31xx - Radeon HD 59xx)
Possibly unless there is a comment in the code as to why a particular chip may be blacklisted.
You may be able to add the definition to the code compile and load the new driver and it would just work assuming the chip is old enough and didn’t do things too differently from existing supported chips… I did this for I think it was Radeon HD 8330 and a couple of the PALM based GPUs in IBM netbooks.
Also in the future why not make your own thread instead of commenting on 8 year old posts?
Try it and see if it works (if you are in a position to recompile the driver and try it), and submit a patch if it does. We try to not enable all devices blindly without anyone testing them before, as it can result in black screen where VESA would have worked out of the box.