Hi,
i have an Radeon HD 7870 GHz Edition graphic card and at finnaly got some 3D and VDPAU acceleration with kernel 3.10, mesa 9.2 from 19.6.2013 and glamor accelerations, but it carsh a lot. I attached dmesg witch hopefully helpful error messages and X.org.log. If you need more information, tell me how and i will try to get it for you.
Regards, Andrej Gelenberg