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I am running Linux on the very cheap iBall Compbook Excelance (an Indian company). Recently I was surprised to find that this laptop apparently has a USB 3.0 interface, or at least a bus. When I run lsusb I get this:

Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 007: ID 15d9:0a4c Trust International B.V. USB+PS/2 Optical Mouse
Bus 001 Device 005: ID 258a:6a88  
Bus 001 Device 004: ID 093a:733a Pixart Imaging, Inc. 
Bus 001 Device 003: ID 05e3:0608 Genesys Logic, Inc. Hub
Bus 001 Device 002: ID 0781:5567 SanDisk Corp. Cruzer Blade
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The first line indicates that there's a USB 3.0 bus. Some online literature also lists the claim that there is one USB 3.0 port, but I can't find out if that's for the specific model I have (the model numbers are unclear).

But the above output applies when things are plugged into both USB ports - the mouse and the pen drive. Since nothing shows up on Bus 002, does this mean there is no external facing USB 3.0 port? In which case I wonder why the bus is there.

Or is it that both of these are USB 2.0 devices (neither is USB 3.0 capable) that leads them to be attached to Bus 001?

Edit: This is the output of lsusb -t:

/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 5000M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/6p, 480M
    |__ Port 1: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 480M
    |__ Port 2: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
        |__ Port 4: Dev 8, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 4: Dev 10, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
            |__ Port 3: Dev 9, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 2: Dev 4, If 0, Class=Video, Driver=uvcvideo, 480M
        |__ Port 2: Dev 4, If 1, Class=Video, Driver=uvcvideo, 480M
        |__ Port 3: Dev 5, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 3: Dev 5, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M

Edit: This question in fact notes that USB 2.0 devices show up as connected to a USB 2.0 hub even if they are in a USB 3.0 port. I'll be getting a 3.0 pen drive in a day or two and will answer this question if that turns out to be the fix.

NB: Incidentally I have read the answers to this very similar question and none of them seems relevant to my question - neither port is blue and neither has SS next to it. But I don't feel like that is conclusive, since this is an extremely cheap laptop and many things are not as per standards.

ShankarG
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  • Added to the question. But you're right, at least for me, it didn't help much. – ShankarG Jan 30 '19 at 12:19
  • I cannot locate any other ports except the two USB ports that are in use and a mini HDMI port. There is a microSD card reader but I presume that is not on the USB bus, since that is also full at present and is not showing up in `lsusb`. I did not disable anything in the BIOS. – ShankarG Jan 30 '19 at 14:45
  • Your point 3 is possible (if disappointing :-( ) though this company makes very few models. But it may be reusing a mobo from another manufacturer. – ShankarG Jan 30 '19 at 14:45
  • However I still am wondering - is the listing perhaps this way because these are USB 2.0 *devices*? Would that make a difference? – ShankarG Jan 30 '19 at 14:46
  • Now I have access to my laptop with few USB 3.0 ports (and few 2.0 only) and I can confirm that slow devices are reported under 480M hub even if in 3.0 socket. Only a 3.0-capable device in a 3.0 socket appears under my 5000M hub. – Kamil Maciorowski Jan 30 '19 at 14:55
  • Ah, thank you. If you post this as an answer I'll accept it. I'll try purchasing a 3.0 device and see what happens. – ShankarG Jan 30 '19 at 15:29

1 Answers1

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If you look at the pinout of an USB 3.0 connector, you'll see that it has a data pair for USB 2.0, and two additional data pairs for USB 3.0.

That's why USB 2.0 (or earlier) devices connected to a USB 3.0 port show up under the USB 2.0: They literally use the USB 2.0 bus that's part of the USB 3.0 connector.

Also note that your USB 3.0 root hub only has a single port (1p), while the USB 2.0 root hub has 6 ports (6p). So it's not unlikely the USB 3.0 root hub with it's single port isn't connected to any of the visible ports.

As you already noted in the comments, the way to find out is to use a real USB 3.0 device and connect it to each port in turn. You can also try to look closely at your visible ports and try to find out if you can see the recessed pins at the back that are used for USB 3.0, even if the ports may not be blue.

dirkt
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