On Mon, 14 Jan 2019, Paul Elder wrote: > On Fri, Jan 11, 2019 at 10:50:11AM -0500, Alan Stern wrote: > > On Fri, 11 Jan 2019, Paul Elder wrote: > > > > > On Wed, Jan 09, 2019 at 02:06:31PM -0500, Alan Stern wrote: > > > > On Wed, 9 Jan 2019, Paul Elder wrote: > > > > > > > > > A usb gadget function driver may or may not want to delay the status > > > > > stage of a control OUT request. An instance where it might want to is to > > > > > asynchronously validate the data of a class-specific request. > > > > > > > > > > A function driver that wants an explicit status stage should set the > > > > > newly added explicit_status flag of the usb_request corresponding to the > > > > > data stage. Later on, the function driver can explicitly complete the > > > > > status stage by enqueueing a usb_request for ACK, or calling > > > > > usb_ep_set_halt() for STALL. > > > > > > > > > > To support both explicit and implicit status stages, a UDC driver must > > > > > call the newly added usb_gadget_control_complete function right before > > > > > calling usb_gadget_giveback_request. To support the explicit status > > > > > stage, it might then check what stage the usb_request was queued in, and > > > > > for control IN ACK the host's zero-length data packet, or for control > > > > > OUT send a zero-length DATA1 ACK packet. > > > > > > > > > > Signed-off-by: Paul Elder <paul.elder@xxxxxxxxxxxxxxxx> > > > > > v4 Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > > > > > v1 Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > > > > > > > This looks good and has passed my tests so far. > > > > > > Good! Thank you :) > > > > > > > Can you check your uvc > > > > changes using dummy_hcd with the patch below? > > > > > > I'm not sure what to make of the test results. I get the same results > > > with or without the patch. Which I guess makes sense... in dummy_queue, > > > this is getting hit when the uvc function driver tries to complete the > > > delayed status: > > > > > > req = usb_request_to_dummy_request(_req); > > > if (!_req || !list_empty(&req->queue) || !_req->complete) > > > return -EINVAL; > > > > > > So the delayed/explicit status stage is never completed, afaict. > > > > I presume you are hitting the !list_empty(&req->queue) test, yes? The > > other two tests are trivial. > > Yes, that is what's happening. > > > Triggering the !list_empty() test means the request has already been > > submitted and not yet completed. This probably indicates there is a > > bug in the uvc function driver code. > > The uvc function driver works with musb, though :/ Did you ever figure out the reason for the "!list_empty(&req->queue)" error with dummy_hcd? Was it related to the confusion about completion callbacks for status requests? Interesting new question: How does your code in musb tell the difference between a 0-length data-stage reply to a control-IN transfer, and a status-stage request? Both would appear to the UDC driver as 0-length request submissions for ep0. Do you explicitly keep track of whether the data stage is pending? Alan Stern
