[XFree86] RV100 driver woes

I've not been able to get a driver to work for an ATI RV100 video 'card' - it's on the motherboard, a Sapphire Axion IGP-320/A3-M275 for AMD. I've tried various combinations, including the radeon driver with XFree86 4.1, and also the ati driver with 4.2.1. From what I can gather it's not

[XFree86] ati/radeon/RV100 driver woes

(apologies if you've already received something like this - I got the addresses wrong) I've not been able to get a driver to work for an ATI RV100 video 'card' - it's on the motherboard, a Sapphire Axion IGP-320/A3-M275 for AMD. I've tried various combinations, including the radeon driver with