Serial Speed change and USB issues on Win10

[PyB]

Hello,

The below might be an awkward issue and not directly related to ChibiOS per say, but I'm posting to see if anyone experienced similar issues.

I have an application developed on top of a Nucleo Board (F446RE). This application uses the STM32 serial connected to STLink and accessible on a computer through a VCP.

The F446RE Uart is initially set @ 921kbps and is working fine. While the application is running, I sometime need to change the UART speed to 115kbps or even 9.6kbps. I do this with sdStop and sdStart. This works fine on most computer I have used (win7, Win8, Linux, ...).

Lately I stumbled upon a strange issue with a couple of Win10 PCs:
- Win 10 PC use the Microsoft Win10 USB VCP driver
- On one PC when I change the speed from 921k to 9.6k it works, but when i change from 921k to 115k it doesn't (the PC still sees the VCP but no data exchange is possible.
- On the other PC when I change the speed (whatever speed) the VCP either disappear (rarely) or the VCP doesnt work anymore (no more data seen)
- Tests were done with a simple term software (TeraTerm)

Any clue where it can come from, it is pretty annoying and probably not really linked to ChibiOS...


Thanks for the help,
PyB