On Fri, 7 Jun 2019, Andrey Konovalov wrote: > > > The problem is that I want to receive that data (from the data stage) > > > from within my gadget driver module. But it's not passed to the > > > setup() callback. And the question is: how do I do that then? > > > > I just caught up on this thread... > > > > The answer is simple: The gadget driver's setup() callback routine > > submits a request for endpoint 0. The Data Stage data is sent or > > received (depending on the direction encoded in the Setup information) > > by this request. > > Ah, OK, got it, thanks! > > Although while looking at the dummy_hcd implementation, I saw that it > accesses usb->transfer_buffer in case USB_REQ_GET_STATUS in > handle_control_request(), which is called right before the setup() > callback is called. So the data already available there without any > additional requests. Is this an implementation detail that is specific > to dummy_hcd? Yes, it is. dummy-hcd is unusual in that it combines both a USB host controller and a USB device controller in a single driver. Normal UDC drivers do handle USB_REQ_GET_STATUS on their own without requiring the use of an explicit usb_request, because they handle the entire transfer internally and don't involve the gadget driver. However, they don't have access to any transfer_buffer; all they can do is exchange packets with the host. Alan Stern
