Read:
The I3C bus receive data stored in the Receive Data Buffer is always aligned to a 4-byte boundary. If the length of the data transfer is not aligned to a 4-byte boundary, then there are extra (unused) bytes at the end of the transferred data. The valid data must be identified using the DATA_LENGTH field in the Response Descriptor.
Write:
The I3C bus transmit data written to the Transmit Data Buffer must be aligned to a 4-byte boundary. If the length of the transfer is not aligned to a 4-byte boundary, then there will be extra (unused) bytes at the end of the transferred data. The I3CC shall only send the valid number of bytes indicated in the DATA_LENGTH field of the Command Descriptor.