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Beginner
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Reading DPCD register data from remotely connected DP1.2 display

Hi,

I am using below reference code in the CUI Doc to read out DPCD register data from a DP-VGA dongle which is connected to the downstream port of DP MST Hub (PC -> DP MST Hub -> DP-VGA dongle).

IGFX_DP_AUX_INFO InData;

DWORD dwError = 0;

ZeroMemory(&InData, sizeof(IGFX_DP_AUX_INFO));

InData.relativeAddress.ucTotalLinkCount = pDisplays->relativeAddress.ucTotalLinkCount;

InData.relativeAddress.ucAddress[0] = pDisplays->relativeAddress.ucAddress[0];

InData.portType = pDPTopology-> PortList[0];

InData.dwOpType = IGFX_REMOTE_AUX_READ;

InData.dwSize = 5;

InData.dwAddress = 0x500;

hr = pCUIExternal8->GetDeviceData((GUID*)&IGFX_GET_SET_REMOTE_AUX_INFO_GUID, sizeof(InData), (BYTE*)&InData, &dwError);

I could see DP MST Hub reading 5 byes DPCD register data from DP-VGA dongle at DPCD register address 0x500 by using DP AUX analyzer and received hr = OK from API call, however the reading back DPCD register data is not stored in the data buffer (InData.Data[]). InData.Data[0] - [131] has all "0" data.

Any comment to solve the issue would be very appreciated.

Thanks,

Eric Lu

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2 Replies
Community Manager
72 Views

Hello EricNXP,

 

 

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 https://software.intel.com/en-us/forums/developing-games-and-graphics-on-intel

 

 

Regards,

 

Fred D.
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Beginner
72 Views

Thanks Fred.

I have posted it to the graphics developer forum, however any feedback is welcome.

Thanks,

Eric Lu

NXP

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