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Linux/TUSB8041: Issue with PWRCTL signal pins

Nikhil Rao82
Prodigy 220 points
Part Number: TUSB8041
Other Parts Discussed in Thread: TPS2561

Tool/software: Linux

Hello,

We have been using the TI TUSB8041IRGC Hub in a new design.  We have developed a number of prototypes (nearly 20 boards) and have been using this TUSB8041 Hub for just over a year.

The Hub is being used for connection to two Type A USB3 ports and to a Wi-Fi and 4G Cellular Modem module.  Communication with the Hub to devices plugged into the Type A ports and also the Wi-Fi and 4G modems are generally fine.

However we have an issue with the PWRCTL pins.  We have interfaced a TI TPS2561DRC Power Switch to the TUSB8041 Hub. We find that the standard Hub power control commands do not normally work with the TUSB8041.  When the command is provided in Linux to toggle the PWRCTL lines (using clear/set  USB_PORT_FEAT_POWER), the voltage on the PWRCTL pins is unchanged.  Basically the PWRCTL pin is always remains high and it never switches off (go to low state).

But when a Type A Port is triggered by an overcurrent event received from the TPS2561 device, the TUSB8041 hub first disables the port power (by toggling the PWRCTL line low to the TPS2561DRC), then sends overcurrent warning to Host CPU.  And after that, no matter what device is plugged into the same port, the USB hub port power off/on command (controlling the PWRCTL signal line) starts to work fine, and keeps working fine.

 

It happens for other ports too (e.g. Wi-Fi port). Initially we cannot control the PWRCTL line.  But once we trigger an overcurrent event, then we can control the port power using Host hub command in Linux which can then drive the PWRCTL line both high and low.

 

I can attach a schematic of our hardware implementation.  Could you kindly provide a support email address?

Is there an errata for the TUSB8041 device? 

Has anyone else experienced a similar issue with the PWRCTL lines not working on the TUSB8041 Hub till the hub is triggered by an overcurrent event?

 

Kind Regards,

 

Nikhil

 

 

  • 0
    TI__Intellectual 1350 points

    Hello Nikhil,

    Could you provide me a schematic of your board to help me understand what is going on?

    Best,
    Gerasimos

  • 0 in reply to Gerasimos Madalvanos66
    Prodigy 220 points

    08 - USB 3 Hub & SDHC.pdf

    Hi Gerasimos, 

    I have attached a schematic of the USB3 Hub in our design.  All circuitry related to the Hub is in this page.  Hopefully with this schematic added, my support query will be easier to understand. 

    Could you also please advise if there is any errata for the TUSB8041? 

    Thank you,

    Nikhil

  • 0 in reply to Nikhil Rao82
    TI__Guru 60865 points
    Nikhil,

    There are no errata for the TUSB8041, but it is compliant to an earlier version of the USB 3.0 specification. This does not impact power control.

    When attempting to control port power using the USB host controller is the driver setting and clearing port power on both the USB 2.0 and USB 3.0 instances of the hub? If the USB 2.0 side of the hub powers off a port, but the USB 3.0 side does not the port will remained powered. When an overcurrent event happens port power may be turned off entirely on one of the port instances (depending on the driver behavior) so the other one can control the port power entirely on its own.

    Regards,
    JMMN
  • 0 in reply to JMMN
    Prodigy 220 points
    Hi JMMN,

    We tried what you have suggested and by turning off both the USB2 and USB3 instances, we can fully utilise the PWRCTL lines (and turn it on/off).

    Thank you for your help.

    Kind Regards,

    Nikhil