https://bugs.freedesktop.org/show_bug.cgi?id=52266
--- Comment #9 from Przemek Tomczyk tomczyk.przemek@gmail.com 2012-07-20 17:14:13 UTC --- neither of those worked. kern.log output is now the same as in first attachement: [drm:radeon_add_legacy_connector] *ERROR* DVI: Failed to assign ddc bus! Check dmesg for i2c errors.
and then
[drm] Connector 1: [drm] DVI-D [drm] HPD2 [drm] DDC: no ddc bus - possible BIOS bug - please report to xorg-driver-ati@lists.x.org [drm] Encoders: [drm] DFP2: INTERNAL_DVO1