I have connected the STM32 USB connector to my Linux PC. lsusb show this port as:
VID/PID: 0x0483/0xdf11 STM32 Defive in DFU Mode
Application specific interface.
It seems that the STM32 on the module responsible for system management and fan control does not have a valid firmware. I still can boot Linux and everything else seems to work fine, also the second port with the serial console.
Is this behaviour expected, or do i need to install a firmware on the STM32?
The STM32 is not responsible for fan control. That is done through the pwm controller attached to FAN0 header. The STM32 has access to read the external temp controllers, attach to the UART, or power on/off the board or reset the board, as well as program the external SPI-ROM for booting. The firmware is still very much a beta and can be found on our github as project-limbs. Alternatively there is another community project called tiny-manager that has less functionality but uses the community driven OpenCM3 stack.