Is there a tested way to update the tone board firmware from linux on raspberry pi or x86? I’ve used dfu-util with other devices in the past, but I’ve not found anything about whether it works with XMOS or not. There are sometimes quirks in implementation, or special things needed to get things into dfu mode. This thread suggests modifying and compiling xmosdfu.cpp from the osx part of the xmos usb audio framework.
Finally: Firmware update