FPGA Intellectual Property
PCI Express*, Networking and Connectivity, Memory Interfaces, DSP IP, and Video IP
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DisplayPort IP comparability issue



I am doing DisplayPort comparability test.

I found Desktop PC included Video card detect right resolution but the some laptop PC which has mini DP or USB-C  doesn't output video signal due to detect wrong resolution. My DP core is non GUP mode so I can't find the problem. I guess the reason of trouble is in DP Link training sequence.

Can you recommend how to solve the problem ? 


Thank you


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I understand in the past you had some issues with your custom board. Then you fixed your board issue and DisplayPort is working after that.

It's not clear to me on your this latest reported issue with DisplayPort compatibility test. Kindly clarify further

  • First of all, pls help me to understand your hardware system setup connection. Example below
    • what GPU model card -> what type of DP cable or what type of DP connection port -> FPGA DP Rx IP -> do you still connect to something else or how you verify the test result ?
    • Pls draw for me the hardware connection diagram and let me know which hardware setup is passing and which hardware setup is failing
  • Are you facing issue with
    • same GPU card system but certain DP port passed and certain DP port failed ?
    • Or different GPU card system. Certain GPU card passed, certain GPU card failed
  • What exactly DP hardware test that you are running ?
    • What DP data rate ? How many DP lanes ?
    • What video resolution ? What bit per colour ? what's refresh rate ?

Assuming your board signal quality is good now, then there are 3 possibility that I think can affect the test result

  • Certain GPU card works, certain GPU card cannot works
    • You need to study the spec of these GPU cards and compare the difference
    • If spec is within supported coverage by Intel DP IP, then maybe is signal integrity issue caused by your board or DP cable. Easy way to isolate potential signal integrity issue by running lower video resolution to force DP IP to run at lower data rate
    • Try use shorter DP cable or different brand DP cable
    • Review your board design again
  • Certain DP port connection works, certain port not
    • FYI... Intel DP IP doesn't support DisplayPort Dual Mode (DP++)
    • It will not work if you are using some converter cable and not direct DP cable
  • Quartus design issue
    • Try upgrade to latest Quartus version to see if it helps
    • Try out DP example design with GPU mode enabled so that you can enabled the debug capability to print MSA log and also NIOS II DP AUX traffic debug log
    • If you are using none GPU mode, I am not sure whether you can still enable DP debug capability or not. Likely you need to depends on external DP protocol analyzer test equipment to analyze the DP AUX traffic




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i haven't been able to solve the DP comparability issue yet, But I added aux_debug_signal capture function and I found the difference between notebook miniDP and Desktop DP.

In notobook miniDP, Training pattern set is 21h (Training pattern 1 and Scrambling disable mode. and Line statues is fail

In the desktop DP, Training pattern set is 01h (Training pattern 1 and Scrambling enable mode and Line status is pass

I attached my own debug capture screen.

Can you recommend why there is different result ?


Thank you


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