USB3.0 loopback hardware failed at full speed loopback

[helloeasyji]

Hi There:

We found different behavior on the Passmark USB 3.0 loopback hardware and would like to get some help here.

--- We have USB extended device ( local and remote device connected by CAT cable, controller is CPLD), and by default it is running at full speed, the 3.0 loopback hardware works well with USBConsole program

--- We also have another USB extended device ( local and remote device connected by multimedia fiber cable, controller is our own design ASIC), and that device works well with 3.0 loopback hardware under high speed mode, but when we use hardware stripping to make it running as full speed, the 3.0 loopback hardware can enumerated as full speed mode, but the loopback test always fail (in both console and GUI). A USB 2.0 flash drive is used to confirm read and write and all works well.
And we used the Passmark 2.0 loopback and Passmark 3.0 loopback hardware to trail run the full speed condition in BurnInTest software, the 2.0 loopback hardware show pass, but the 3.0 loopback hardware always fail.

Please do favor to share some advice.

Thank you.

Ping

[helloeasyji]

Here is the error logs, thanks.

I actually cut some of the logs lines to reduce the file size

[David (PassMark)]

First of all can you confirm the terminology you are using.
"running a full speed" in ambiguous in the world of USB standards. It is much clearer to use the Mbps number.

Here is the naming of speeds

• USB 1.0/Low-Speed: 1.5 Megabits per second (Mbps)
• USB 1.1/Full-Speed: 12 Mbps
• USB 2.0/Hi-Speed / High speed: 480 Mbps
• USB 3.0/SuperSpeed: 5 Gbps
• USB 3.1/SuperSpeed+: 10 Gbps (also called "SuperSpeed USB 10Gbit/s")
• USB 3.2/SuperSpeed+: 20 Gbps (also called "SuperSpeed USB 20Gbit/s" )
• USB 4/USB4 20Gbit/s or USB4 40Gbit/s

So I am assuming you are trying to run the USB3 plug at USB1 speeds (12Mps). But then it doesn't work with your in house extender at 12Mbps. But does work at USB2 480Mbps speeds. But then you attempt to prove your extender works at USB1 12Mbps speeds by connecting a USB2 480Mbps flash drive. This doesn't make much sense to me. If you want to test USB1 speeds you need a USB1 flash drive.

With the USB3 loopback plug that you have can you check that the USB1 lines are working correctly.
In the USB3Test software, there is an option to force USB1 12Mbps behaviour from the user interface. Can you test that the USB3 plug works at USB1 speeds on a standard USB port, without any extender. If the plug works OK without the extender, and doesn't work with the extended, then it would seem to be a fairly safe assumption that the extender has a problem.

[helloeasyji]

Hi David,

Thanks for the feedback and sorry for the confusion caused. Here I revised some terminology in my question:

--- We have USB extended device ( local and remote device connected by CAT cable, controller is CPLD), and by default it is running at full speed 12Mbps, the USB 3.0 loopback hardware works well with both USBConsole and GUI with 12Mbps

--- We also have another USB extended device ( local and remote device connected by multimedia fiber cable, controller is our own design ASIC), and that device works well with USB 3.0 loopback hardware under high speed 480Mbps mode, but when we changed one of the hardware strapping to make our designed extender running as full speed 12Mbps, the USB 3.0 loopback hardware can enumerated as full speed 12Mbps mode ( which can be seen in GUI and USBViewer), but the loopback test always fail (in both console and GUI). A USB 2.0/1.1 flash drive is used to confirm read and write and all works well with 12Mbps.
And we used the Passmark 2.0 loopback ( CY7C68013A) and Passmark 3.0 loopback hardware to trail run 12Mbps ( connected through our fiber version extender device to host) in BurnInTest software, the 2.0 loopback hardware show pass, but the 3.0 loopback hardware always fail.

--- The previous fail log I posted is captured in USB 3.0 Tester GUI software , with USB 3.0 loopback hardware and running at 12Mbps.

[David (PassMark)]

I noticed this in the log
Mon Nov 08 12:02:18 2021: Diagnostics- ISO Packets/PI changed to 1 due to selecting a HS/FS device

Are you running the USB3 plug in isochronous mode?
Nearly all other USB devices (Flash drives, our USB2 plug, etc...) run in bulk mode.

Did you trying running in Bulk mode with the USB3 plug?

Maybe your extender device has a problem with isochronous mode at USB1 speeds?
(and to be honest nobody uses the old USB1 speeds and nobody uses isochronous mode, so it is a rare combination)

[helloeasyji]

Thanks David for sharing the observation. I will talk to my FW team what's the default feature bit is tuned on in FW.

One interesting observation is the same extender with same FW works perfectly with Passmark 2.0 loopback ( CY7C68013A) with 12Mbps, not sure what's the reason behind that.

For the Passmark 3.0 loopback console API, may i know if we can change the coding of full speed data type to ISO as well, just like the high speed category?

[helloeasyji]

Hi David,

By accidently i found the benchmark testing can pass with the extender and USB 3.0 hardware under 12Mbps speed, may i have some information about the difference between benchmark and loopback?

Thank you.

[David (PassMark)]

same FW works perfectly with Passmark 2.0 loopback ( CY7C68013A) with 12Mbps, not sure what's the reason behind that.

As mentioned above, it would be using bulk transfer mode. So if the problem was limited isochronous mode at 12Mbps, then you wouldn't see the problem.

may i know if we can change the coding of full speed data type to ISO as well

I'm confused. Isn't that what you are already testing?

[helloeasyji]

As mentioned above, it would be using bulk transfer mode. So if the problem was limited isochronous mode at 12Mbps, then you wouldn't see the problem.



I'm confused. Isn't that what you are already testing?

Hi David,

Please disregard my question on API, and sorry for the confusion.