Now I’m evaluating iMX8M-Plus with Dahlia Board (v1.1A) for one of our new projects. I want to measure the performance of USB ethernet gadget to see if USB 3.0 benefits on the module.
Currently I’m on tdx-reference-minimal-image with RT patch:
uname -a
Linux verdin-imx8mp-06848948 5.4.129-rt61-5.4.0-devel+git.cca85a46277d #1 SMP PREEMPT_RT Wed Aug 11 11:58:56 UTC 2021 aarch64 GNU/Linux
What is the most practical way of testing USB 3.0 for ethernet gadget on the board? I need X3 connector on the Dahlia board to test which is directly interfaced by Verdin SOM. Other USB port is connected to a Microchip USB HUB which will slow down the performance I assume.
I have noticed that tdx-reference-minimal-image doesn’t include usb ethernet gadget available in: ./layers/meta-toradex-bsp-common/recipes-support/libusbgx/files/g1.schema.in
I modified tdx-reference-minimal-image.bb file and added packagegroup-tdx-cli into IMAGE_INSTALL. Now g1.schema file and related services are installed. Default schema file came with toradex-bsp configured to enable RNDIS instead of NCM that I need.
I modified g1.schema file to be as below (which I assume it enables USB 3.1 and NCM):
USB_1 interface (exposed by the USB type-C connector X3) is not SuperSpeed capable.
USB_2 interface (exposed by the USB type-A connector X4) is SuperSpeed capable.
So, if I understood correctly, as the USB gadget on the module would be seen as a device to, let’s say, the computer that it will be connected to, having the SuperSpeed at the USB type-A isn’t suitable for you.
To use this interface as a gadget, you would need to design your own carrier-board. Or maybe, if possible, keep using Dahlia, but with a limited transfer rate.