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TPS65994AE: DP monitor display compatibility issue.

CJ Kao
Prodigy 75 points
Part Number: TPS65994AE

Tool/software:

Hi 

           We found a DP monitor cannot display compatibility issue related TPS65994AE behavior.

           TPS65994AE will update 0x5F value from DP mode to USB3 mode when DP monitor update "HPD state = low" and "Exit DP = No" during type C to DP cable is connected.

           We’d like to know what kind of condition TPS65994AE will switch to USB3 mode?

           We also check DP alt spec that did not define DP mode must switch to USB3 mode condition when “conn bit from 1 to 0”.

 

           Is there any setting to setup mode switch condition in GUI tool?

           65994AE FW version is vF609_06_09.

           Thank you.

  • 0
    TI__Genius 12905 points

    I recommend first starting with latest GUI tool and FW version as currently that FW is 6 releases behind. You can find the updated GUI with the latest release here: https://www.ti.com/drr/opn/TPS65994-DESIGN 

  • 0 in reply to Christodulos Tsongas
    Prodigy 75 points

    thanks, but the project was MP.

    We are looking for minimize modify to fix.

    Could we modify some settings of the current FW to change the behavior?

  • 0 in reply to Christodulos Tsongas
    Prodigy 75 points

    We checked the latest GUI tool version is 6.4.32 and latest FW is vF609_06_12.

    We still can duplicate the issue.

  • 0 in reply to CJ Kao
    TI__Genius 12905 points

    CJ,

    The Device (monitor) is sending the HPD_L:ow which is a display disconnect. IF this is the case, then there is not much we can do to support this as this would be the monitor powering off. 

    Can you share your PJT so I can look at it? 

    Also please answer some basic questions:

    • Are you following a reference design? 
    • Do you know what is triggering monitor to send HPD_LOW? 
    • Is the display working after transaction 23 above? 

    Thanks,

    Chris

  • 0 in reply to Christodulos Tsongas
    Prodigy 75 points

    Hi Chris,

           Sure, I would share the PJT to you.

           May I share on E2E forum?

    • Are you following a reference design? 

               CJ: Yes, the design is ASM4242 with TPS65994AE.

    • Do you know what is triggering monitor to send HPD_LOW? 

               CJ: when used Unigraf UCD-400 to test DP CTS. that will toggle HPD.

    • Is the display working after transaction 23 above? 

               CJ: Yes.

           Thanks,

  • 0 in reply to CJ Kao
    TI__Mastermind 18015 points

    Hi CJ,

    Give us some time to look into this!

    Thank you,

    Kevin

  • 0 in reply to Kevin Kosta
    TI__Genius 12905 points

    CJ,

    The monitor is sending the HPD_Low and disconnect information. If this is the case, the 'HPD' signal is lost and PD sees no connection. If monitor sends another HPD High, then we would re-detect the monitor. I am not sure this is a PD issue at this point. If you have the ability to I suggest trying some of the following options:

    • Windows Display Settings -> Detect option can help wake up a monitor sometimes
    • From the monitor, See if you can get it out of sleep mode by turning it off and on (NOT power-cycling)
      • OR 
    • See if you can switch input types this usually causes HPD High to be sent again. 

    Thanks,

    Chris

  • 0 in reply to Christodulos Tsongas
    Prodigy 75 points

    Hi Chris,

         Could you review our PJT file in private message?

         Is there any GUI option to modify the exit DP mode condition?

         

         In this case the monitor did not send HPD High after 994 set config to USB.

         Thank you.

  • 0 in reply to CJ Kao
    TI__Genius 12905 points

    CJ,

    Are you just wanting to exit DP mode in this scenario?

    The monitor is required to send the HPD High signal. We have set the DP Config to USB because the DP Monitor asserted HPD Low AND set the Conn State as Nothing. This means there is no need for DP video mode because the monitor is not sending data to PD/Host. 

    Thanks,

    Chris

  • 0 in reply to Christodulos Tsongas
    Prodigy 75 points

    Hi Chris,

         We'd like to keep in DP mode in this scenario.

         Is there an option of GUI tool to control 994AE exit DP mode to USB mode behavior until received "Exit DP = Yes"?

         Thank you.

  • 0 in reply to CJ Kao
    TI__Genius 12905 points

    You can use the Alternate Mode Tasks 4CC commands to send VDM commands, Send Exit and Enter commands. Check out the AMEn, AMEx, AMDs, GCdm, and VDMs commands for control of this. 

    Thanks,

    Chris

  • 0 in reply to Christodulos Tsongas
    Prodigy 75 points

    Hi Chris,

         Could we modify PJT file to implement the behavior?

         If that cannot implement in PJT file, please kindly provide 4CC CMD example let us reference?

         Thank you.

  • 0 in reply to CJ Kao
    TI__Mastermind 18015 points

    Hi CJ,

    4CC commands are explained in the TRM!

    Basically this would be implemented by an external EC writing the command to the PD controller.

    Thank you,

    Kevin

  • 0 in reply to Kevin Kosta
    Prodigy 75 points

    Hi Kevin,

         The problem is DP monitor did not display when monitor toggle HPD=low when cable is keep connected.

         According previous discuss, DP monitor stay in DP mode but 994AE switch to USB3 mode when detect HPD=low and connection = nothing.

          I think monitor and host in different state cause the link training fail.     

         May I know how to identify USB4 host should be enter USB3 mode or re-enter DP mode in this case?

         Could we have chance to patch the monitor compatibility issue through PD FW?

         Thank you.

         CJ

  • 0 in reply to CJ Kao
    TI__Genius 12905 points

    CJ, 

    Kevin is out currently so expect some delayed responses. 

    CJ Kao said:
     I think monitor and host in different state cause the link training fail.

    From the DP Config message, it seems monitor is fully disconnecting. HPD=Low would not break a USB3 connection. However I think the DP monitor setting connection = Nothing is causing the USB3 break. 

    I do have a suggestion though, it looks like monitor is being configured for full-duplex (pin E). If you enable 'Multi-function preferred' in the DP Config register, I suspect PD will have a configuration of pin D, E or F. These would be half-duplex in that 2 HSS are used as DisplayPort, 2 are used as USB3. This may get the connection working? 

    CJ Kao said:
    May I know how to identify USB4 host should be enter USB3 mode or re-enter DP mode in this case?

    USB3 entry would be determined by the Discover Identity response from the UFP and cable information. However, PD does support USB3 mode without the need for actual PD USB3 entry. IF you read-back DataStatus after the HPD = low and connection = nothing, we can verify this. 

    CJ Kao said:
    Could we have chance to patch the monitor compatibility issue through PD FW?

    This may be a monitor issue in that it fully turns off. I wuld expect HPD = low for turning off display, but connection = nothing is what is causing the full disconnect.