sdk2.0.0: PICO_STDIO_USB_ENABLE_RESET_VIA_VENDOR_INTERFACE=0 incompatible with CDC

[UKTailwind]

As per the title, My application was using this parameter in previous releases (1.5, 1.6) with no issues. On rebuilding with sdk2.0.0 the application didn't work (see https://forums.raspberrypi.com/viewtopic.php?p=2243782#p2243782) and this was tracked down to this setting. Adding the parameter to the build of hello-usb proved the problem

[kilograham]

I added PICO_STDIO_USB_ENABLE_RESET_VIA_VENDOR_INTERFACE=0 to hello_usb and it still enumerates fine (at least on Ubuntu)... @will-v-pi can you give it a spin on windows

Are you using stdio_usb or custom CDC?

[will-v-pi]

I can confirm this is broken on Windows - I upgraded the bcdUSB to 210 to support WinUSB drivers for the reset interface, but this means Windows doesn't recognise the device without that enabled (PICO_STDIO_USB_RESET_INTERFACE_SUPPORT_MS_OS_20_DESCRIPTOR). I'll push a PR to switch bcdUSB back to 200 if that isn't enabled

[kilograham]

So what exactly changed in 2.0.0 that broke this?

[will-v-pi]

It was changing bcdUSB from 0x0200 to 0x0210 - when bcdUSB is 0x0210 on Windows then it requires the MS_OS_20 descriptors, which I added to the reset interface for driverless picotool on Windows.

So if you're not using the reset interface MS_OS_20 descriptors it needs to remain at 0x0200 else Windows does not recognise the USB device.

[lurch]

I think this was fixed on develop by #1857 , so can this be closed now @will-v-pi ?