https://bugs.freedesktop.org/show_bug.cgi?id=105433
--- Comment #4 from Michel Dänzer michel@daenzer.net --- (In reply to Thomas R. from comment #3)
[drm] dce_get_required_clocks_state: clocks unsupported disp_clk 681000 pix_clk 148500
FWIW, I get the same message with Tonga, with a single DVI connection. I haven't noticed any obvious ill effects related to it though, so it might not be relevant for this issue.