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TUSB8041 USB3 and CDP issue?

Oliver Talevski
Prodigy 20 points

Other Parts Discussed in Thread: TUSB8041

Dear,

Have you noticed any issues with connecting a USB3 device to the CDP port? I am using a HP Z440 as host machine and connect a USB3 smartphone to the CDP port in the front. My issue is that when I connect my Lumia 950 to the USB3 CDP it first enumerates correctly as SuperSpeed CDP 1500mA but then VBUS is removed by host (TUSB8041) and applied again but this time it enumerates as SuperSpeed SDP 500mA. Same behaviour with Windows and Linux on host side. I have also verified same behaviour with an Android device.


Regards,

Oliver

  • 0
    TI__Guru 60870 points

    Hi Oliver,

    Are you only seeing this issue with the HP Z440 host machine?  The TUSB8041 hub has CDP capability that can be enabled, but while the upstream port is actively connected to a host the TUSB8041 should not discharge the VBUS unless directed to do so by the host controller.  It is possible that there is a USB battery charging controller in the path that is handling the CDP mode and causing the discharge event.

    On a side note, all the USB BC 1.2 CDP handshaking occurs over the USB 2.0 signal lines, so I'm not sure how that would be properly  implemented on a device that is connected via the USB 3.0 lines. 

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 20 points
    Hi,
    Yes I only see this when connected to the Z440. I have verified that USB3+CDP works on HP ZBook (Intel controller). The Android device is a development unit so I can disable USB3 on this and then USB2+CDP works with Z440.
    I know the handshake is done on D+/D- but this handshake is done before the USB enumeration. So it seems that CDP is first agreed but then when USB3 is enumerated the VBUS is dropped and SDP+USB3 is the result. We have this same behaviour on 3 different workstations (Windows 7 and Linux Ubuntu/Mint).

    Connecting Microsoft Lumia 950 to HP Z440 with Linux Mint:
    [11856.688128] usb 4-4.1: new SuperSpeed USB device number 17 using xhci_hcd
    [11856.707122] usb 4-4.1: New USB device found, idVendor=045e, idProduct=0a00
    [11856.707127] usb 4-4.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
    [11856.707131] usb 4-4.1: Product: Lumia 950 (RM-1104)
    [11856.707133] usb 4-4.1: Manufacturer: Microsoft
    [11856.707136] usb 4-4.1: SerialNumber: 51000000872B65DB0000000000000000
    [11857.954998] usb 4-4.1: USB disconnect, device number 17
    [11862.819819] usb 4-4.1: new SuperSpeed USB device number 18 using xhci_hcd
    [11862.841065] usb 4-4.1: New USB device found, idVendor=045e, idProduct=0a00
    [11862.841071] usb 4-4.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
    [11862.841074] usb 4-4.1: Product: Lumia 950 (RM-1104)
    [11862.841077] usb 4-4.1: Manufacturer: Microsoft
    [11862.841079] usb 4-4.1: SerialNumber: 51000000872B65DB0000000000000000

    Before the disconnect we have USB3+CDP (1500mA) and after the disconnect we have USB3+SDP (500mA).

    Regards,
    Oliver
  • 0 in reply to Oliver Talevski
    TI__Guru 60870 points
    Hi Oliver,

    The behavior you are describing does not sound like the embedded CDP function of the TUSB8041. It appears that there is a standalone battery charging controller in the path. I will try to loop the USB battery charging team into this thread.

    Regards,
    JMMN