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TUSB564RNQEVM: Can't Enable 4 Lane DP

Tom Wang1
Prodigy 50 points
Part Number: TUSB564RNQEVM
Other Parts Discussed in Thread: TUSB564

Hi,

I'm trying to enable 4k@60 over 4-lane DP on this EVM. My source and sink can work with 4k@60, if I use type C to HDMI converter. However, EVM can only output 4k@30 from the same source to the same sink. DP cable has been verified to support DP 1.4. 

The GPIO (CTL0, CTL1) from TPS65986 to TUSB564 stayed at H and H, meaning it's one port USB 3 + 2Lane DP, and this status does not change. 

The event mapped to GPIO 0 (USB 3 Event) and GPIO 1 (DP Mode selection) do not seem to respond accordingly. 

Even by putting jumper on these two GPIO to force it into 4 Lane DP, only 4k@30 is the max resolution available.

THanks.

  • 0
    TI__Guru 64326 points

    Hi Tom,

    What EQ settings have you tried? It is possible that your DP link is failing link training at 4k@60. What kind of cables are you using to test with the EVM?

  • 0 in reply to Malik Barton57
    Prodigy 50 points

    Hi Malik,

    I've tried DPEQ upto 5.4dB gain according to jumper setting on Table 7 in datasheet. 

    DP port is connected through a DP 1.4 to HDMI 2.0 cable, so the BW isn't the bottleneck.

    Also re-route the SBU to AUX through TPS65986 on the EVM, instead of TUSB564, does not change the CTL0 and 1 status.

    When mux is forced to be in 4-Lane DP by putting in the jumper, there is a billboard message saying USB port reset failed.

    Thanks.   

  • 0 in reply to Tom Wang1
    Prodigy 50 points

    Hi Malik,

    I can see how register bits get updated when type C-C is plugged into host PC.

    Since the host type C includes,

    USB3

    USB2

    DP ALT

    If GPIO0 and GPIO1 are mapped to USB3 event and DP mode selection event, then both bits are H, resulting in 2-lane DP+USB 3, all the time.

    Ultimately, my question is when will the GPIO change to 4-lane, by mapping to what event?

    Thanks. 

  • 0 in reply to Tom Wang1
    Prodigy 50 points

    Hi Malik,

    I figured out a way to toggle the 2-lane and 4-lane.

    One thing I discovered is that when 4-lane is switched back to 2-lane, USB3 is not re-enumerated. 

    Any idea how to fix it?

    Thanks.

  • 0 in reply to Tom Wang1
    TI__Guru 64326 points

    Hi Tom,

    Sorry for the late reply here. When you swtich from 4-lane back to 2-lane are you reconnecting the USB 3 device? Does the device work at USB 2?

  • 0 in reply to Malik Barton57
    Prodigy 50 points

    Hi Malik,

    USB3 is unplugged and plugged back in, but enumeration seemed to get stuck, because it did not go to USB2 after USB3 not being enumerated. 

    USB3 camera is also used and same behavior as above.

    Using a USB2 only device verified that USB2 enumeration is ok.

    Thanks.

  • 0 in reply to Tom Wang1
    TI__Guru 64326 points

    Hi Tom,

    Are you able to use a USB protocol Analyzer to help debug this situation? This will help us determine what is holding up the USB 3 enumeration. If not you can also use a high speed scope to monitor the Superspeed lanes and see what activity may be there, if any.