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TPS65987D: About the settings in DisplayPort capabilities, and behavior of ELECOM DisplayPort adapter (AD-CDPBK)

user1585882
Prodigy 100 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TPS65987

Hi, I'm an engineer of laptop PC product. Please call me Takki.

Now my team are working on products using TPS65987DDH.

Application customization tool is ver5.1.
Some our products support USB Gen2 and TBT3, and others support USB Gen1 and DP alt Mode.

We realized that when we connect ELECOM Type C-DP adapter(AD-CDPBK) to our products, video output success-or-fail is depend on the settings in DisplayPort Capabilities[0x51] bit 10 and 11.

DisplayPort Capabilities[0x51] bit 10=Supports DP v1.3 signaling
DisplayPort Capabilities[0x51] bit 11=Supports USB Gen 2 signaling
 
After "Enter Mode", DFP(TPS65987) sends "DP Configure Message".
Then, UFP returns "DP Configure ACK Message".

"DP Configure Message" contains DP v1.3 bit and USB Gen2 Signal bit, and the status of each bit is just the same as the settings in DisplayPort Capabilities[0x51] bit 10 and 11.

According to the settings, the video output success-or-fail will change.
Please see the table bellow.

　 Supports Gen2 Signaling
check box
F/W 0x51 [11]		 Supports DP v1.3
Signaling
check box
F/W 0x51 [10]		 Gen2 : DP v1.3
bit status
in "DP Configure Message" from DFP(TPS65987)		 Output Result
Pattern1 レ レ 1:01 DP Output NG
Pattern2 レ 　 1:00 DP Output NG
Pattern3 　 レ 0:01 DP Output OK
Pattern4 　 　 0:00 DP Output NG

When the output succeeds, UFP(AD-CDPBK) returns ACK as a "DP Configure ACK Message" .
When the output fails, UFP(AD-CDPBK) returns NAK as a "DP Configure ACK Message", and DFP(TPS65987) issues "Exit Mode", and then alternate mode is ended.

Now we are thinking about changing the setting of DP capabilities [0x51] bit 10 and 11 so that AD-CDPBK can output images.

 But we have some questions.

1. What are the influences if the USB Gen2 bit in 0x51 is un-checked.
  (If we use USB Gen2 device without DP alt mode, is this bit ignored?)
  (If we use USB Gen2 device with DP alt mode, is the speed limited to Gen1?)

2.DFP(TPS65987) set the DP v1.3 bit and  USB Gen2 Signal bit in "DP Configure message" according to DisplayPort Capabilities[0x51] bit 10 and 11. Is it appropreate behavior as DFP?
  (DFP could know the capabilities of UFP device by receiving "Discover Mode ACK message", so we think these bits may need to be changed to the current available sigals.)


Besides, if you know, please answer the bellow question.

3. ELECOM AD-CDPBK return NAK when the "DP Configure message" is defferent from its expectaion.  Is it appropreate behavior as UFP?

Now, we will soon have to take TBT3 compliance test. After the test, we cannot change our TPS65987 F/W images.

So please reply as soon as possible. I will contact TI Japanese sales team.


Thank you

  • 0
    TI__Mastermind 36756 points
    Hi Takki-san,

    I would suggest updating to the latest GUI tool on Ti.com. It should be Version 5.13.

    1. What are the influences if the USB Gen2 bit in 0x51 is un-checked.
    If you use a USB Gen 2 device without DP alt mode, then that bit is ignored.
    The speed should not be limited, the PD controller would have no effect on the USB data speed.

    2. This looks like correct behavior for the DFP

    3. This does not sound like expected behavior from the UFP.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 100 points
    Hi, Mr.Eric. Thank you for your reply.

    About the first quesiton,
    You wrote "The speed should not be limited, the PD controller would have no effect on the USB data speed."
    Is it also true when we use Gen2 device with DP alt mode?

    And I have additional question.

    When the UFP returns NAK as a "DP Configure ACK Message", then TPS65987 issues "Exit Mode".
    Is it also appropreate behavior as DFP?
    Can we force TPS65987 to ignore the NAK?

    Thank you,
    Takki
  • 0 in reply to user1585882
    TI__Mastermind 36756 points
    Hi Takki-san,

    Is it also true when we use Gen2 device with DP alt mode?
    - Only if you enter a DP Pin assignment that supports both DP and USB3.

    When the UFP returns NAK as a "DP Configure ACK Message", then TPS65987 issues "Exit Mode".
    Is it also appropreate behavior as DFP?
    Can we force TPS65987 to ignore the NAK?
    - Yes, this is expected behavior. We cannot change the behavior of the TPS65987 to ignore the NAK.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 100 points
    We enter DP pin assignment that supports both DP and USB3.0.
    In this case, although we uncheck the "Supports Gen2 Signaling", we can use USB Gen2 speed and DP video output simaltaneously, is it right?
  • 0 in reply to user1585882
    TI__Mastermind 36756 points
    Hi Takki-san,

    That is correct, you can use both USB3.0 and DP in that case.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 100 points

    Hi, Mr. Eric

    Thank you for your answer.

    We will use the settings as I mentioned in the former post.
    (DisplayPort Capabilities[0x51] bit 10=Supports DP v1.3 signaling       1b
    DisplayPort Capabilities[0x51] bit 11=Supports USB Gen 2 signaling   0b.)

    Thank you.