As mentioned in the description with dc=0 the error does not occur. I've tested amd-staging-drm-next from current HEAD (efb7936df2efe1434f0d5e72ae9d256a4388965a) and the error still occurs. With this kernel I see following error in dmesg: [drm:construct [amdgpu]] *ERROR* construct: Invalid Connector ObjectID from Adapter Service for connector index:2! type 0 expected 3