USB3 test drops connection from 5Gb/s to 480Mb/s in Linux BurnInTest v3.1

[DWRidder]

I have Linux BurnInTest v3.1 (1002) that I am running in 64bit (as chosen by the shell script). I plugged my loopback plug into the USB3 port and it reads ~5.0 volts and 5Gb/s. I then set the test to only run the USB test with 1 USB plug and 50 cycles. As soon as I start the test the speed drops to 480Mb/s. I stop the test and the speed stays at 480Mb/s.

I am running the test on a Lenovo T61 laptop with a ExpressCard USB3 plug-in card. I need to unplug the card and plug it back in to get back to 5Gb/s speed.

Why won't it test at full speed?
Why is forcing the USB port to go to USB2 settings?

[Tim (PassMark)]

Before the test starts the USB3 plug has to be configured which requires it to re-enumerate, it sounds like there may be an issue in Linux with the driver for the USB3 card you are using that is stopping the plug re-enumerating correctly.

Could you please email us a copy of the dmesg log after you have connected the USB plug and started a test.

Are you able to test the card in Windows using USB3Test to see if the behavior is different?

[DWRidder]

I sent the log in an email.

I am not able to test on Windows because I cannot use the same ExpressCard on my Windows machine (a Lenovo T420) since its ExpressCard slot only takes 33mm cards and the one I'm using in the Lenovo t61 is a 54mm card.

[DWRidder]

Here is the most relevant part of the log:

//Plugged in USB3 ExpressCard here:
[336421.090957] hub 8-0:1.0: USB hub found
[336421.090975] hub 8-0:1.0: 2 ports detected
[336421.091141] xhci_hcd 0000:05:00.0: xHCI Host Controller
[336421.091285] xhci_hcd 0000:05:00.0: new USB bus registered, assigned bus number 9
[336421.093896] xHCI xhci_add_endpoint called for root hub
[336421.093903] xHCI xhci_check_bandwidth called for root hub
[336421.093987] hub 9-0:1.0: USB hub found
[336421.094003] hub 9-0:1.0: 2 ports detected
[336421.344156] hub 8-0:1.0: unable to enumerate USB device on port 2
[336421.584811] usb 9-2: new SuperSpeed USB device number 2 using xhci_hcd
// Started test here:
[336445.785918] usb 9-2: reset SuperSpeed USB device number 2 using xhci_hcd
[336445.802120] usb 9-2: device firmware changed
[336445.802197] usb 9-2: USB disconnect, device number 2
[336445.802402] xhci_hcd 0000:05:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff880036da3c00
[336445.802411] xhci_hcd 0000:05:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff880036da3c40
[336445.802420] xhci_hcd 0000:05:00.0: xHCI xhci_drop_endpoint called with disabled ep ffff880036da3c80
[336446.868090] usb 8-2: new high-speed USB device number 3 using xhci_hcd

[Tim (PassMark)]

After some more debugging over email it appears the most likely cause of the issue is that the express card slot on the laptop in use was V1, which does not have enough bandwidth to support 5Gb/s USB3 speeds.