USB speed is capped to Full Speed when using a custom UTMI PHY

greatscottgadgets / luna

Amaranth HDL framework for monitoring, hacking, and developing USB devices

https://greatscottgadgets.com/cynthion/

BSD 3-Clause "New" or "Revised" License

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USB speed is capped to Full Speed when using a custom UTMI PHY #276

Open jeanthom opened 2 months ago

jeanthom commented 2 months ago

Hi,

I recently noticed that when using Luna with a custom UTMI PHY, it would limit itself to USB FS. The limit is a hardcoded value:

https://github.com/greatscottgadgets/luna/blob/6a8d1e5448e2e4683e403d69fc4eadf25e5c0934/luna/gateware/usb/usb2/device.py#L118-L123

There is no technical limitation preventing us from doing USB HS: we tested a modification of these constants successfully with a ULPI-UTMI translator.

Jean