How to downgrade USB to full speed (12MBits/s)


I occasionally connect an USB device with long wires of bad quality to a Jetson Nano. This device claims itself as an USB2 device. As a consequence, high speed (480MBits/s) is used over these wires. I don’t need such a speed so I’d like to force the USB host port of the Jetson Nano not to exceed full speed (12MBits/s).

I know this can be requested in the generic USB entry of the device tree. The line maximum-speed = “full-speed” is supposed to do the job. I used it successfully with another hardware.

My problem is that I cannot figure out where it can be specified with the Jetson platform. I have tried in the entry xusb and also in the entries xusb_padctl / pads / ports. But it fails to force full speed.

Any hint on how to do this ?

Thank you,
Best regards,

The easiest thing to do is to get a USB 1.1 HUB. I’m not sure if there is a way to downgrade without that. Plugging a USB 2 device into a USB 1.1 HUB, and then the HUB into the Jetson, will automatically revert to 1.1 (12Mb/s). There may be a device tree method, but I do not know what the change would be.

Thank you for your answer. That’s likely one solution. I’ll write here if I find a pure software solution.

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