From: Leo Li <sunpeng.li@xxxxxxx> [Why] DCN is the display hardware for amdgpu. DRM planes are backed by DCN hardware pipes, which carry pixel data from one end (memory), to the other (output encoder). Each DCN pipe has the ability to blend in a cursor early on in the pipeline. In other words, there are no dedicated cursor planes in DCN, which makes cursor behavior somewhat unintuitive for compositors. For example, if the cursor is in RGB format, but the top-most DRM plane is in YUV format, DCN will not be able to blend them. Because of this, amdgpu_dm rejects all configurations where a cursor needs to be enabled on top of a YUV formatted plane.
