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TPS65987D: Alternate-mode sometimes won't work properly

Maurice
Intellectual 971 points

Part Number: TPS65987D

Hi, everyone,

We designs PC & tablet using TPS65987DDH.

Now, we have trouble with PC when attaching PD monitor.
Sometimes PD monitor is still dimmed.

And we've noticed something wrong with PDC.
- HPD won't become HI, when PD monitor is attached,

　even if  PD negotiation is finnished properly. (We've checked "EnterMode" is issued)

- High voltage Warning (0x29 register) becomes HI, only when we remove PD device.

 (Sometimes, both of High / Low Voltage Warnings become HI.)

And also, we know HPD becomes HI and Voltage Warnings are cleared,

if we reset PD controller by HRESET pin or software reset command (4CC).

[Question]

(1) Why HPD won't become HI even if PD monitor is attached?

(2) Are there any tips to clear High / LowVoltageWarning?
Status (0x29) register is for read only, so we cannnot change these bits by EC.

(3) Are there any countermeasures against this problem?

And are there any relation between HPD failure & High/LowVoltageWarning?

(4) We are planning to use "4CC" command as the countermeasure (SW reset).

 For examle, "GAID".

 Could you tell us what "4CC" command is best?

Because we're worried about side-effect of "4CC" commands.

Best Regards,

  • 0
    TI__Mastermind 36756 points

    Hi Maurice,

    1. Are you seeing the DP Attention message through PD communication? We will not set HPD high unless we receive the DP attention message from the monitor.

    2. The High/low voltage warning bits are not related to DisplayPort mode and have no effect on displayport.

    3. There are no relations with high/low voltage warning and HPD. If we do not receive the DP Attention message from the monitor, we will not toggle HPD. This is aligned with the DP alt mode spec.

    4. The 4CC command "GAID" will force the PD controller to do a reboot and reload the configuration from the SPI Flash.

    If this answers your question, PLEASE select This resolved my issue

    Thank you,
    Eric

  • 0 in reply to Eric Beljaars
    Intellectual 971 points

    Hi, Eric-san,

    >1. Are you seeing the DP Attention message through PD communication?

    >We will not set HPD high unless we receive the DP attention message from the monitor.

     

    Of course we saw PD negotiation.

    HPD won't become HI, even if DP attention message can be seen.

    (And also, there's no difference about PD negotiation data

    whether alternate mode work properly or not.)

    I'll send you log data by private mail later, please confirm them.

    >4. The 4CC command "GAID" will force the PD controller to do a reboot

    >and reload the configuration from the SPI Flash.

    How about "Gaid" command ?

    Please tell us what "Gaid" command does.

  • 0 in reply to Maurice
    TI__Mastermind 36756 points

    Hi Maurice,

    Are you using physical HPD (GPIO) or virtual HPD over I2C? Are you saying that you see the HPD attention message in PD but the TPS65987D does not toggle the GPIO or send the HPD message over I2C? The TPS65987D will only set the HPD GPIO high when we receive the DP Attention message in PD. Additionally, if the HPD GPIO is high and there is no display, it could be something else in the system causing the issue.

    The Gaid command will force a warm reboot of the PD controller, in this case, it will reload the configuration from the device RAM and return to its original bootup configuration.

    If this answers your question, PLEASE select This resolved my issue

    Thank you,
    Eric

  • 0 in reply to Eric Beljaars
    Intellectual 971 points
    Hi, Eric-san,


    >Are you using physical HPD (GPIO) or virtual HPD over I2C?
    We're using physial HPD (GPIO).

    >Are you saying that you see the HPD attention message in PD
    >but the TPS65987D does not toggle the GPIO or send the HPD message over I2C?

    Yes. When we connect our designing products (using TPS65987DDH) to PD monitor,
    we can see DP attention message,
    but HPD won't become HI.
    (though PD negotiation looks finished properly)


    Our base firmware is F707.10.05



    Best Regards,
  • 0 in reply to Maurice
    TI__Mastermind 36756 points
    Hi Maurice,

    I cannot reproduce this issue on my EVM no matter which Type-C monitor I am using. Can you try to reproduce this on the EVM?

    Thanks,
    Eric
  • 0 in reply to Eric Beljaars
    Intellectual 971 points
    Hi, Eric-san,


    Unfortunately, we cannot have reproduced this phenomenon on the EVM.


    And also, we're worrying about High/Low Voltage Warning becomes 1.
    So could you answer to these question?

    - Are there any tips to clear High / LowVoltageWarning?
    Status (0x29) register is for read only, so we cannnot change these bits by EC.

    - When does High/LowVoltageWarning become available?
    (For example, after load from SPI ROM has finneshed.)


    Best Regards,
  • 0 in reply to Maurice
    TI__Mastermind 36756 points
    Hi Maurice,

    The high/low voltage warning would become available after the PD controller had loaded from the SPI Flash. Please keep in mind that the High/Low Voltage warning has no effect on the PD controller behavior. It is simply used as a status bit to indicate the voltage level to the system. The high/low voltage warning level can be adjusted in register 0x28.

    Thank you,
    Eric