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TUSB8041: Question for TUSB8041 3.0 port can not detect devices when switching OS between Windows and Android

Jacky Wang(QD)
Genius 9930 points
Part Number: TUSB8041

Hi Experts,

Our customer is using TUSB8041 in a TV project with dual OS, Windows and Android. During their test, they found one issue is when switching between Windows and Android OS, there is high possibility that TUSB8041 3.0 port can not detect devices when inserted into one of four down-streaming ports. Even we pull low GRST pin after the OS switching, it still can not detect devices after inserting to 3.0 port.

Attached is customer's schematic for TUSB8041 section, can you help to review it and give us some comments what's the problem in here?

TUSB8041 Schematic_8-4-2020.pdf

Thanks.

  • 0
    TI__Guru 60865 points

    Hi Jacky,

    I believe the downstream USB 3.0 devices are entering compliance mode which would not be cleared by a reset to the hub only.  The only way to bump the downstream devices out of compliance mode is to toggle VBUS to the devices low or to reset them directly.  Can the customer confirm this fixes the behavior so we can confirm root cause? 

    To prevent the devices from entering compliance mode, USB_VBUS to the hub should be low during the operating system change or the hub should be held in reset while the operating system is changed.  If USB_VBUS is left high and the hub is active, the hub may leave its downstream rx terminations on which confuses the downstream devices.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Genius 9930 points

    Hi JMMN,

    We tried to follow your suggestion to toggle VBUS but it doesn't work. Attached is customer's USB bus communication log captured by Beagle USB 5000 v2 Superspeed Protocol Analyzer, can you help to review them and locate the root cause for this issue? Thanks.

  • 0 in reply to Jacky Wang(QD)
    TI__Guru 60865 points

    Hi Jacky,

    Can you provide full logs to me and explain which one matches which behavior?  You can send directly to me via private message.  I will send you a friend request.

    Regards,

    JMMN

  • 0 in reply to JMMN
    TI__Guru 60865 points

    Downstream ports of the hub are entering compliance mode.

    Feedback being provided directly.

    Closing ticket.