Comment # 6 on bug 111261 from Fab Stz

The issue seems to be related to these calls in file
amdgpu-19.30-855429/amd/display/amdgpu_dm/amdgpu_dm.c

twice:
kcl_drm_dp_cec_unset_edid(&aconnector->dm_dp_aux.aux);

once:
kcl_drm_dp_cec_set_edid(&aconnector->dm_dp_aux.aux,
                                            aconnector->edid);

If I delete them the display works also with 19.30