Hi,
Alan Stern stern@rowland.harvard.edu writes:
So I am not sure how the Gadget driver can figure out that it needs to usb_ep_queue() another request for status stage when handling the no-data control?
Gadget drivers already queue status-stage requests for no-data control-OUT requests. The difficulty comes when you want to handle an IN request or an OUT request with a data stage.
I don't see a difficulty there. Gadget driver will see wLength and notice it needs both data and status stages, then it does:
usb_ep_queue(ep0, data_req, GFP_KERNEL); usb_ep_queue(ep0, status_req, GFP_KERNEL);
Just needs to prepare both requests and queue them both ahead of time. UDC drivers should hold both requests in their own private list and process one at a time.