Custom xxx_xfer_cb never called

[WerWolv]

Hi!
I'm trying to write a driver for a USB class with a Bulk In, a Bulk Out and a Interrupt In endpoint. Currently testing on a STM32L4 board using the stm32_fsdev backend.

It's possible that I just don't understand tinyusb well enough yet but in Wireshark I can see the Host sending e Bulk Out request to the second endpoint and a Interrupt In request to the third endpoint. My expectation is now that the xxx_xfer_cb function of my class driver would be called, delivering that data to me so I can handle it and respond to it. However, neither of these requests seem to arrive in the event queue at all. Is this a configuration setup issue or misunderstanding of the library on my side or what could cause this?

Thanks a lot for the help

[WerWolv]

Okay I believe I figured it out mostly.

The key information I was missing is that in order to receive any data on the device, I have to call usbd_edpt_xfer with the endpoint I want to receive data from. Then once the IN or OUT request from the host arrives, the xxx_xfer_cb function is finally executed and (in the case of a OUT request) the buffer is populated with the received data.

Not sure if this is the way you're supposed to do it but I managed to get things working by just having a xxx_process() which is called in the same while loop tud_task() is being called in:

void xxx_process(void) {
  xxx_interface_t *itf = &_xxx_itf[0];
  if (!itf->open) return;

  if (!usbd_edpt_busy(0, itf->ep_bulk_out)) {
    usbd_edpt_claim(0, itf->ep_bulk_out);
    usbd_edpt_xfer(0, itf->ep_bulk_out, itf->bulk_out_buffer, sizeof(itf->bulk_out_buffer));
  }
}

[hathach]

yup, usbd_edpt_xfer() must always be called for both IN & OUT for tx/rx. Check out other driver for ref