Expected DCD events following tud_disconnect()?

[projectgus]

When implementing the MicroPython dynamic USB support for RP2040, I relied on the behaviour that calling tud_disconnect() on a connected and configured USB device causes a DCD_EVENT_BUS_RESET event to be delivered. This resets internal USB device driver state while the USB device is "soft disconnected", until calling tud_connect() later.

(There's an open issue where this doesn't work on RP2040, but it's worked in MicroPython when I've tested it.)

On ESP32-S3 we're finding that no events are delivered after calling tud_disconnect() - as a result device drivers still have their connected state (in particular, CDC thinks it's connected).

Searching issues it seems like something similar happens with other DCD drivers as well (no event comes to tell the devices they are disconnected).

I was wondering if there are any events expected after calling tud_disconnect(), in general? (If so, missing events may be a bug.)

I'm also wondering if it would be reasonable for TinyUSB to always call dcd_event_bus_reset() or dcd_event_bus_signal(..., DCD_EVENT_UNPLUGGED) to inject an event when tud_disconnect() is called on a configured device. Then the device driver state can update correctly even if the hardware doesn't provide any event?

[projectgus]

Some extra context from the MicroPython perspective: micropython/micropython#18375 (under "Related Bugs")

[HiFiPhile]

I think it's something we've overlooked, in dcd_disconnect we just disable the pull-up resistor, if we are lucky some port will send a unplugged event.

I think we need to do something like this (untested):

diff --git a/src/device/usbd.c b/src/device/usbd.c
index 05fc752af..5a8d51bbe 100644
--- a/src/device/usbd.c
+++ b/src/device/usbd.c
@@ -476,12 +476,16 @@ bool tud_remote_wakeup(void) {
 }
 
 bool tud_disconnect(void) {
+  dcd_int_disable(_usbd_rhport);
   dcd_disconnect(_usbd_rhport);
+  usbd_reset(_usbd_rhport);
+  tud_umount_cb();
   return true;
 }
 
 bool tud_connect(void) {
   dcd_connect(_usbd_rhport);
+  dcd_int_enable(_usbd_rhport);
   return true;
 }