Created attachment 94711 [details]
bios_dump

I've bought a radeon HD 7750 with 4 mini-DP Connectors and use passive hdmi
adapters to connect my 3 Monitors.

kernel version is 3.13.5

on bootup kernel reports:

Feb 25 10:42:32 barfoos24 kernel: radeon 0000:05:00.0: Invalid ROM contents
Feb 25 10:42:32 barfoos24 kernel: ATOM BIOS: C44501

After init of drm the montiors goto black.

After reading a lot i managed to get them working by following kernel params:

radeon.modeset=1 radeon.dpm=1 video=DP-1:1920x1200-24@60D
video=DP-2:1920x1200-24@60D video=DP-3:1920x1200-24@60D
rm_kms_helper.edid_firmware=edid/1920x1200.bin

edid/1920x1200.bin is self compiled edid.

i've attached the dumped bios.

in this configuration the card is working with all 3 monitors, but after
screenlog or a console change the screens remain dark.

the kernel log reads:

Feb 25 10:44:01 barfoos24 kernel: [drm:radeon_dp_link_train_cr] *ERROR* clock
recovery failed
Feb 25 10:44:01 barfoos24 kernel: [drm:radeon_dp_link_train_cr] *ERROR*
displayport link status failed
Feb 25 10:44:01 barfoos24 kernel: [drm:radeon_dp_link_train_cr] *ERROR* clock
recovery failed
Feb 25 10:44:01 barfoos24 kernel: [drm:radeon_dp_link_train_cr] *ERROR*
displayport link status failed
Feb 25 10:44:01 barfoos24 kernel: [drm:radeon_dp_link_train_cr] *ERROR* clock
recovery failed
Feb 25 10:44:01 barfoos24 kernel: [drm:radeon_dp_link_train_cr] *ERROR*
displayport link status failed