2 Replies Latest reply on Nov 24, 2015 3:33 AM by kknd

    DisplayPort Downspread

    kknd

      Hello guys,

       

      I'm developing the DisplayPort receiver product now.

      And i use NVIDIA & AMD graphic cards for the compatibility test of my product.

       

      Because my product do not support the DP Downspread, i turn off the DP Downspread of graphic cards.
      According to my test result, my product works fine with NVIDIA card but do not work with AMD card. (I use a Radeon R9 270.)

      I have some questions as below.


      1. Do AMD Graphic cards always activate the DP Downspread?


      2. Is there a control function of the DP Downspread in the AMD Driver?


      3. Is it correct that AMD card generate the DP Signal by the DPCD Information?

        • Re: DisplayPort Downspread
          ray_m

          Unfortunately, this question is far too technical and I am unable to find any information on this in my local resources.

           

           

          I would suggest you address your question to the actual manufacturer of your graphics card.

           

          I can however, confirm that the AMD Display Driver does not have an option to control DP Downspread.

          1 of 1 people found this helpful
            • Re: DisplayPort Downspread
              kknd

              Thank you very much for your answers and advice!

               

              In addition, I have one more question.
              Do AMD Graphic card comply with the below contents of Display Port Standard?

              ==================================================
              2.2.3.1 De-spreading of the Regenerated Stream Clock
              Support for down-spreading of the link frequency (with modulation frequencies of 30 kHz or 33 kHz) to
              minimize EMI is required for Sink Devices compliant with the DisplayPort specification. Support for

              downspreading by Source Devices is an implementation decision and is optional.
              A DisplayPort Sink Device must indicate whether it is capable of supporting a down-spread link frequency

              in the DPCD by either setting or clearing the MAX_DOWNSPREAD bit.
              For a certain Sink Device, such as an audio Sink Device, the regenerated stream clock must not have

              downspreading.
              Such Sink Devices must perform de-spreading when regenerating the stream clock. The method of
              de-spreading is implementation specific.
              ==================================================

              If you or anyone can not give me answer, Does this question also should be sent to actual manufacturer of my graphic card like my first

              questions?