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TUSB8041: Programmatically disable USB3 on TUSB8041

Haydn Philpotts
Prodigy 20 points
Part Number: TUSB8041

We've developed a base for an Android tablet. The base contains a TUSB8041 USB hub that's hard wired to a Microchip LAN7801 USB-Ethernet controller. It's also connected to a USB3 port to allow other devices to be attached.

We're experiencing an issue where on some of our bases the USB3 connection drops out. This results in a loss of Ethernet connectivity. However if we mask out the USB3 pins on the bottom of the tablet and force a USB2 connection to the hub the problem does not occur.

We're not exactly sure why this problem occurs but as an interim solution we'd like to force the TUSB8041 hub into USB2 only mode. Are there any registers available on the hub that would allow us to do this programmatically via a Linux driver?

  • 0
    TI__Guru 60870 points
    Hi Haydn,

    Yes, there are some known EMI issues with USB 3.0. Mainly the problems are related to interaction with wireless devices however. We do not have a way to disable USB 3.0 in the hub via a command.

    Do you have access to the TUSB8041 registers via SMBUS or EEPROM? I was wondering if disabling SSC would help (Register F0h, bit 0) - I know this is counter-intuitive, but it could be the range of the spread is impacting the Ethernet controller.

    Regards,
    JMMN
  • 0 in reply to JMMN
    Prodigy 20 points

    Hi, thanks for your response. Our hardware team has found that there was a problem with noise occurring on the flexi cable linking the USB docking pins on the base to the main board. Fixing this should solve our problem. Thanks for your assistance.