From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F027C43387 for ; Fri, 18 Jan 2019 16:31:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F238A20850 for ; Fri, 18 Jan 2019 16:31:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="U3bMpzTX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728341AbfARQbS (ORCPT ); Fri, 18 Jan 2019 11:31:18 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:53804 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727346AbfARQbS (ORCPT ); Fri, 18 Jan 2019 11:31:18 -0500 Received: from localhost.localdomain (unknown [96.44.9.117]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id E642153E; Fri, 18 Jan 2019 17:31:13 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1547829075; bh=8hr+puCZKU3CkrjGCLHvQPZ4wsY5ygkfShhzYrcLtgQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=U3bMpzTXF2MmTDhR/baQlxW7nGIo2hBsH4DFYjZ5dOBjLHZCnrq9vzD3TRDi44E7b q5VhRRI3eqcc84O7OUXtLQ4xoFVUsukzjOlPdHjx82u9qdIOgH2vifv5oSQOsX8aPa MNRLM45UrIycGtY/B+aHggs+RfHEdrAneQ5Wxpxs= Date: Fri, 18 Jan 2019 11:31:06 -0500 From: Paul Elder To: Alan Stern Cc: laurent.pinchart@ideasonboard.com, kieran.bingham@ideasonboard.com, b-liu@ti.com, rogerq@ti.com, balbi@kernel.org, gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 4/6] usb: gadget: add mechanism to specify an explicit status stage Message-ID: <20190118163106.GC7331@localhost.localdomain> References: <20190116050029.GA13084@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 16, 2019 at 10:06:53AM -0500, Alan Stern wrote: > On Wed, 16 Jan 2019, Paul Elder wrote: > > > On Mon, Jan 14, 2019 at 10:24:44AM -0500, Alan Stern wrote: > > > On Mon, 14 Jan 2019, Paul Elder wrote: > > > > > > > > > > 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 :/ > > > > > > > > I compared the sequence of calls to the uvc setup, completion handler, > > > > and status stage sending, and for some reason dummy_hcd, after an OUT > > > > setup-completion-status sequence, calls a completion-status-completion > > > > sequence, and then goes on the the next request. musb simply goes on to > > > > the next request after the setup-completion-status sequence. > > > > > > I don't quite understand. There's a control-OUT transfer, the setup, > > > data, and status transactions all complete normally, and then what > > > happens? What do you mean by "a completion-status-completion > > > sequence"? A more detailed description would help. > > > > > > > I meant the functions (procedures) in the function driver, so the setup > > handler (uvc_function_setup), the completion handler > > (uvc_function_ep0_complete), and the status sender (uvc_send_response), > > although the last one actually sends the data stage for control IN. > > So after the status is sent on the uvc gadget driver's end, its > > completion handler is called again without the setup handler being > > called beforehand and I cant figure out why. > > Isn't this what you should expect? Every usb_request, if it is queued > successfully, eventually gets a completion callback. That promise is > made by every UDC driver; it's part of the gadget API. So for a > control transfer with a data stage, you expect to have: > > Setup handler called > Data-stage request submitted > Data-stage request completion callback > Status-stage request submitted > Status-stage request completion callback > > Thus, two completion callbacks but only one setup callback. omg how did I not notice this :/ I guess I have to fix the uvc function driver so it works with that. musb doesn't call the status stage completion callback though; not that it does anything so it seems fine to me, but indeed the function driver has to be ready for it if it is called. > > > > I commented out the paranoia block in dummy_timer, and dummy_hcd still > > > > does the extra completion, but it doesn't error out anymore. I doubt > > > > that's the/a solution though, especially since I get: > > > > > > > > [ 22.616577] uvcvideo: Failed to query (129) UVC probe control : -75 (exp. 26). > > > > [ 22.624481] uvcvideo: Failed to initialize the device (-5). > > > > > > > > Not sure if that's a result of dummy_hcd not supporting isochronous > > > > transfers or not. > > > > > > > > I'm not sure where to continue investigating :/ > > > > > > Perhaps removing the "#if 0" protecting the dev_dbg line in > > > dummy_queue() would provide some helpful output. > > > > It did, but didn't get me much farther :/ > > > > > Another thing to check would be if the "implement an emulated > > > single-request FIFO" in dummy_queue() is causing trouble. There's no > > > harm in replacing the long "if" condition with "if (0)". > > > > That didn't change anything. > > > > Although I did notice that the dummy_queue that calls the completion > > handler without the preceeding setup handler says that it's in the > > status stage (ep->status_stage == 1). > > That is consistent with the events outlined above. Thanks, Paul