https://bugs.freedesktop.org/show_bug.cgi?id=27314

--- Comment #42 from Jérémy Lal kapouer@melix.org 2011-05-10 18:28:22 PDT --- I think the problem comes from the difference between BIOS run (working): drm:radeon_dp_get_link_status], link status 11 11 80 00 00 00 [drm:radeon_dp_link_train], clock recovery at voltage 0 pre-emphasis 0 [drm:radeon_dp_get_link_status], link status 77 77 81 00 00 00 [drm:radeon_dp_link_train], channel eq at voltage 0 pre-emphasis 0

and EFI run (black screen): [drm:radeon_dp_get_link_status], link status 00 00 00 00 11 11 [drm:dp_get_adjust_train], requested signal parameters: lane 0 voltage 0.6V pre_emph 0dB [drm:dp_get_adjust_train], requested signal parameters: lane 1 voltage 0.6V pre_emph 0dB [drm:dp_get_adjust_train], requested signal parameters: lane 2 voltage 0.6V pre_emph 0dB [drm:dp_get_adjust_train], requested signal parameters: lane 3 voltage 0.6V pre_emph 0dB [drm:dp_get_adjust_train], using signal parameters: voltage 0.6V pre_emph 0dB [drm:radeon_dp_get_link_status], link status 00 00 00 00 22 22

Though I'm a bit weak on atombios_dp.c, i'm ready to promptly test any patch. Last test was with kernel 2.6.39-rc6.