title: STM32 VCP on Linux is super slow
body: <p>I use the USB OTG device on my STM32F407-Discovery to send and receive data with pyserial - using the USB CDC interface provided by STM32CubeMX. On Windows (with ST VCP drivers), I get a very decent speed that suit my needs. Running a python script that sends/receive the same string (a sort of 'echo' from/to the STM32), it takes about 3 seconds to complete the test, with 10000 packets.</p>
  
  <p>On Linux, using /dev/ttyACM0, it takes 30 seconds. That means the speed on Linux is about 10x less. Changing the baudrate with stty doesn't seem to have any effect. This was tested on Ubuntu 17.10 with VirtualBox.</p>
  
  <p>I wonder, how can I make the serial port on Linux as fast as on Windows?</p>
  
  <p>Thanks!</p>