This message was posted on behalf of Intel Corporation
I understand you are trying to read out DPCD register data from a DP-VGA dongle.
Let me apologize for any inconvenience this issue may be causing to you.
I recommend contacting our graphics developers so they can assist you better. You can post your inquiry on this forum https://software.intel.com/en-us/forums/developing-games-and-graphics-on-intel