I have a FreeBSD 9.2 system on which I am developing a USB3 data acquisition 
card (based on the Cypress FX3) and I have found that it doesn't reliably 
connect at 5GBps - quite often it seems to only connect at 480MBps.

If I connect it to my macbook pro (running OSX) it reliably connects at 5Gbps.

Since the FreeBSD system doesn't have onboard USB3 I purchased 2 PCIe USB3 
cards. I wanted to see if there was a difference in behaviour between the 2 
cards but that doesn't seem to be the case.

xhci0@pci0:3:0:0:       class=0x0c0330 card=0x34321106 chip=0x34321106 rev=0x03 
xhci1@pci0:5:0:0:       class=0x0c0330 card=0x70521b6f chip=0x70521b6f rev=0x00 

xhci0: <XHCI (generic) USB 3.0 controller> mem 0xfbeff000-0xfbefffff irq 17 at 
device 0.0 on pci3
xhci0: 32 byte context size.
usbus1 on xhci0

xhci1: <XHCI (generic) USB 3.0 controller> mem 0xfbcf8000-0xfbcfffff irq 17 at 
device 0.0 on pci5
xhci1: 64 byte context size.
usbus2 on xhci1

Also, when it does connect at 5Gbps the speed seems quite slow - on my laptop 
(with USB controller VID 0x8086 PID 0x9c31 - Lynx point I think) I get 
225MB/sec using libusb. On FreeBSD I get around 92MB/sec although only after 
lowering(!!) the amount read per transfer.

I booted a 10.0 DVD and it seems to behave the same way.

I also tried a USB 3 HD enclosure and it frequently connects at 480MBit as well 
so I don't think it's an issue with the firmware I wrote.

Does anyone have a recommendation, or a path to debugging it?


Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C

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