There is a description in Reference Manual about DC.
Data oriented signals - The DC may add markers to data sent to the DI. These
markers are used to indicate a specific attribute of the data (for example: end-of-line,
end-of-frame, chip-select etc.). The marker coming from the DC triggers a specific
waveform of one or more signals on the display's interface. The specific waveform
will be seen on the bus along with the associated data. The markers may be synced to a time oriented signal. For example: attach the end-of-frame signal to the next
1. What is this marker for? Does this marker use only internally for DI or output to some pins?
2. How does these markers add? Are there some control registers?