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=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 10181C5AE5E for ; Sat, 19 Jan 2019 01:03:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA4432087E for ; Sat, 19 Jan 2019 01:03:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547859811; bh=IzNjGriP0u4PrgB7NL5PHiRzpKK9jBrrt77KtG4hO6Y=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=okcEQs6eU1i55cBdljsTBy4+XK4Z66yDeDTcygNd9V3Z9Fjtk+G10nCIrHQ8TqlbI ISoLDjpkl8Jh95tN8UnL2omzHZW0u8W0qC49lmZ7KVbtWZCUfiNbobKzfiU4y7tkCm mnHGw3NOyq/pFOwxBgEuaSuLA+VNw2/+sESSyBPw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727223AbfASBD3 (ORCPT ); Fri, 18 Jan 2019 20:03:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:52106 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726325AbfASBD3 (ORCPT ); Fri, 18 Jan 2019 20:03:29 -0500 Received: from [192.168.1.112] (c-24-9-64-241.hsd1.co.comcast.net [24.9.64.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2DE4320850; Sat, 19 Jan 2019 01:03:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547859808; bh=IzNjGriP0u4PrgB7NL5PHiRzpKK9jBrrt77KtG4hO6Y=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=SoQwIKaxUAkdzBTXOwDN4qMi5unjbg0La32sNNA1rDYTCCLUReS6dsvTKZqZNUInh I026Lec+hK0BsqkEbjOlKiFOAcvCVjfVvLCeIElodSxLiNKWJSjF6aJa1i3bpzcpuH u+RxdLGgqQUlz8Mx38KUt5kYXmrG+o0kCEn+Cs8Y= Subject: Re: [PATCH v9 4/4] sound/usb: Use Media Controller API to share media resources To: Hans Verkuil , mchehab@kernel.org, perex@perex.cz, tiwai@suse.com Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org, shuah References: <2fb40852e4035b2a58010ce7416448918f12804f.1545154778.git.shuah@kernel.org> From: shuah Message-ID: <8593299c-b80f-d1d3-9a03-d56fb1573f60@kernel.org> Date: Fri, 18 Jan 2019 18:03:25 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/18/19 2:54 PM, shuah wrote: > On 1/18/19 1:36 AM, Hans Verkuil wrote: >> On 12/18/18 6:59 PM, shuah@kernel.org wrote: >>> From: Shuah Khan >>> >>> Media Device Allocator API to allows multiple drivers share a media >>> device. >>> This API solves a very common use-case for media devices where one >>> physical >>> device (an USB stick) provides both audio and video. When such media >>> device >>> exposes a standard USB Audio class, a proprietary Video class, two or >>> more >>> independent drivers will share a single physical USB bridge. In such >>> cases, >>> it is necessary to coordinate access to the shared resource. >>> >>> Using this API, drivers can allocate a media device with the shared >>> struct >>> device as the key. Once the media device is allocated by a driver, other >>> drivers can get a reference to it. The media device is released when all >>> the references are released. >>> >>> Change the ALSA driver to use the Media Controller API to share media >>> resources with DVB, and V4L2 drivers on a AU0828 media device. >>> >>> The Media Controller specific initialization is done after sound card is >>> registered. ALSA creates Media interface and entity function graph nodes >>> for Control, Mixer, PCM Playback, and PCM Capture devices. >>> >>> snd_usb_hw_params() will call Media Controller enable source handler >>> interface to request the media resource. If resource request is granted, >>> it will release it from snd_usb_hw_free(). If resource is busy, >>> -EBUSY is >>> returned. >>> >>> Media specific cleanup is done in usb_audio_disconnect(). >>> >>> Signed-off-by: Shuah Khan >>> --- >>>   sound/usb/Kconfig        |   4 + >>>   sound/usb/Makefile       |   2 + >>>   sound/usb/card.c         |  14 ++ >>>   sound/usb/card.h         |   3 + >>>   sound/usb/media.c        | 321 +++++++++++++++++++++++++++++++++++++++ >>>   sound/usb/media.h        |  74 +++++++++ >>>   sound/usb/mixer.h        |   3 + >>>   sound/usb/pcm.c          |  29 +++- >>>   sound/usb/quirks-table.h |   1 + >>>   sound/usb/stream.c       |   2 + >>>   sound/usb/usbaudio.h     |   6 + >>>   11 files changed, 455 insertions(+), 4 deletions(-) >>>   create mode 100644 sound/usb/media.c >>>   create mode 100644 sound/usb/media.h >>> >> >> >> >>> +int snd_media_device_create(struct snd_usb_audio *chip, >>> +            struct usb_interface *iface) >>> +{ >>> +    struct media_device *mdev; >>> +    struct usb_device *usbdev = interface_to_usbdev(iface); >>> +    int ret; >>> + >>> +    /* usb-audio driver is probed for each usb interface, and >>> +     * there are multiple interfaces per device. Avoid calling >>> +     * media_device_usb_allocate() each time usb_audio_probe() >>> +     * is called. Do it only once. >>> +     */ >>> +    if (chip->media_dev) >>> +        goto snd_mixer_init; >>> + >>> +    mdev = media_device_usb_allocate(usbdev, KBUILD_MODNAME); >>> +    if (!mdev) >>> +        return -ENOMEM; >>> + >>> +    if (!media_devnode_is_registered(mdev->devnode)) { >> >> It looks like you missed my comment for v8: >> >> "You should first configure the media device before registering it." >> >> In other words, first create the media entities, and only then do you >> register the media device. Otherwise it will come up without any alsa >> entities, which are then added. So an application that immediately >> opens the media device upon creation will see a topology that is still >> in flux. > > Yes. You are right. I saw your comment and thought I got it addressed. > I will fix it. I have the logic correct in au0828, but not here. > One thing to mention here is some ALSA entities get created dynamically during PCM open when stream is initialized. This happens after media device is registered. These get deleted when pcm close happens. There is no way to avoid creating entities after media device register. snd_media_device_create() could get called after media_device_register() happens, if au0828 registers it first. I did find a problem in snd_media_device_create() and I will send a v10 with that fix. thanks, -- Shuah