Source can't output the video format to HDMI 1.4 Sink, which is a CEA mode with higher VIC than what is defined in CEA-861-D
As an example, a HDMI 1.4 sink has the video format 2560x1080p to be displayed and the video format is indicated by both SVD (with vic 90 and pictuure aspect ratio 64:27) and DTD.
When connecting to such sink, source may not output the video format in SVD because an error is returned by drm_hdmi_avi_infoframe_from_display_mode(), which can't fill the infoframe with pictuure aspect ratio 64:27 and the vic, which is originally 90 and is changed to 0 by drm_mode_cea_vic().