There is no output from the MIPI port of DES even though there is no error indicator asserted. What can be the cause? What to check?

Ensure that the serializer and deserializer are programmed correctly, check lane map, polarity, number of lanes, datatypes etc. Make sure you have PCLKDET on serializer and video_lock on deserializer.

Ensure that CSI output is not disabled by the control bit "CSI_OUT_EN".