STM32 F1 DFU example code

[matswebjorn]

I have a question on libopencm3-examples\examples\stm32\f1\lisa-m-1\usb_hid\usbhid.c .

It defines

static enum usbd_request_return_codes dfu_control_request( usbd_device *dev, struct usb_setup_data *req, uint8_t **buf, uint16_t *len, void (**complete)(usbd_device *dev, struct usb_setup_data *req)) { (void)buf; (void)len; (void)dev;
if ((req->bmRequestType != 0x21) || (req->bRequest != DFU_DETACH))
return USBD_REQ_NOTSUPP; /* Only accept class request. */
*complete = dfu_detach_complete;
return USBD_REQ_HANDLED;
}`

Which is registered in USBD using

usbd_register_control_callback( dev, USB_REQ_TYPE_CLASS | USB_REQ_TYPE_INTERFACE, USB_REQ_TYPE_TYPE | USB_REQ_TYPE_RECIPIENT, dfu_control_request);

My question is, why does dfu_control_request() check bmRequestType with

if ((req->bmRequestType != 0x21) ?

usb_control_request_dispatch() filters requests on the registered request-type using

if ((req->bmRequestType & cb[i].type_mask) == cb[i].type)

So the check in dfu_control_request() is redundant and just confusing for the reader.

It would be nice if the callback typedefs in libopencm3/include/libopencm3/usb/usbd.h
Had the same kind of doxygen declaration as the other functions. This would most
Likely eliminate these kind of misunderstandings of what the presumptions of the callback was.