DLPU082B August 2021 – August 2022 DLPC7540
When the I2C master requests a data read, the Busy flag (7 the bit in the header byte) indicates the short status. If it is set, it means that the DLPC is busy and does not have a response to send back yet. The host can use the System busy pin as a check for the controller's availability to receive. When this bit is set, the rest of the bits of the response header shall be treated as don't care and no further bytes to be read. The expectation is that the host will keep reading from the Controller for response until this bit is cleared. When that occurs the response header is valid, and remaining data is as per the command.
If the host abandons a read command midway or sends another command immediately after sending read command, the response bytes in the controller buffer gets discarded and the new command gets processed.
For USB communication layer, the controller indicates the busy status by NAK response to the read request.