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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 24C1BC282D6 for ; Wed, 30 Jan 2019 07:42:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1CC920869 for ; Wed, 30 Jan 2019 07:42:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730081AbfA3HmY (ORCPT ); Wed, 30 Jan 2019 02:42:24 -0500 Received: from lb1-smtp-cloud7.xs4all.net ([194.109.24.24]:49709 "EHLO lb1-smtp-cloud7.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725819AbfA3HmX (ORCPT ); Wed, 30 Jan 2019 02:42:23 -0500 Received: from [192.168.2.10] ([212.251.195.8]) by smtp-cloud7.xs4all.net with ESMTPA id okVlgyxI3BDyIokVpgtpVt; Wed, 30 Jan 2019 08:42:22 +0100 Subject: Re: [PATCH v10 0/4] Media Device Allocator API To: shuah , 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 References: <481787e7-112a-80dd-228c-2497a12547b9@kernel.org> From: Hans Verkuil Message-ID: Date: Wed, 30 Jan 2019 08:42:17 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfC1iiIVuahTVxwYNG40X1zEK+9nMKOHAiDRD5PFTZiKQbqqMraBMMYeWBuzIhMXIUQHUh4D6RGn4IgaGyXtm30KSw7LrkoSsNaU+xi50/ef7kmuHUPc2 oD03UhE9qy5CsqBrs7FV7UjFTG6a4YYhY07NW6fF9ADl6HY6rnoEesXMXAvvBNNbr2KXo0uf+lno7GlcMtbVDTL13b/UpeqV9TrguospbZNPx1sPX4ik/PMz /WP2joPK89NpeFv6yNcaNVxmgW08xWhlW+/Bfl06VLxDsfB5vNZcoyfctHy8eimxsUyab/qX+ChKYtz3pW1yUwvqWrHChK4h7JMat4Dvjb3p64q1vP8Z28l7 Dvr3YGdowx2jKFYIBD9+IEFNdQPkdQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/30/19 2:50 AM, shuah wrote: > On 1/29/19 2:43 AM, Hans Verkuil wrote: >> On 1/29/19 12:48 AM, shuah wrote: >>> Hi Hans, >>> >>> On 1/28/19 5:03 AM, Hans Verkuil wrote: >>>> Hi Shuah, >>>> >>>> On 1/24/19 9:32 PM, Shuah Khan wrote: >>>>> 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. >>>>> >>>>> - This patch series is tested on 5.0-rc3 and addresses comments on >>>>> v9 series from Hans Verkuil. >>>>> - v9 was tested on 4.20-rc6. >>>>> - Tested sharing resources with kaffeine, vlc, xawtv, tvtime, and >>>>> arecord. When analog is streaming, digital and audio user-space >>>>> applications detect that the tuner is busy and exit. When digital >>>>> is streaming, analog and audio applications detect that the tuner is >>>>> busy and exit. When arecord is owns the tuner, digital and analog >>>>> detect that the tuner is busy and exit. >>>> >>>> I've been doing some testing with my au0828, and I am confused about one >>>> thing, probably because it has been too long ago since I last looked into >>>> this in detail: >>>> >>> >>> Great. >>> >>>> Why can't I change the tuner frequency if arecord (and only arecord) is >>>> streaming audio? If arecord is streaming, then it is recording the audio >>>> from the analog TV tuner, right? So changing the analog TV frequency >>>> should be fine. >>>> >>> >>> Changing analog TV frequency would be s_frequency. The way it works is >>> any s_* calls would require holding the pipeline. In Analog TV case, it >>> would mean holding both audio and video pipelines for any changes >>> including TV. >>> >>> As I recall, we discussed this design and the decision was to make all >>> s_* calls interfaces to hold the tuner. A special exception is g_tuner >>> in case of au0828. au0828 initializes the tuner from s_* interfaces and >>> its g_tuner interfaces. Allowing s_frequency to proceed will disrupt the >>> arecord audio stream. >>> >>> Query (q_*) works just fine without holding the pipeline. I limited the >>> analog holds to just the ones that are required. The current set is >>> required to avoid audio stream disruptions. >> >> So I am not sure about that ('avoid audio stream disruptions'): if I >> stream video AND use arecord, then I can just set the frequency while >> streaming. Doesn't that interrupt audio as well? And are you sure changing >> the tuner frequency actually disrupts audio? And if audio is disrupted, >> are we talking about a glitch or is audio permanently disrupted? > > I think it is a glitch. I will run some tests and let you know. >> >> That's basically the inconsistent behavior I noticed: just running arecord >> will prevent me from changing the frequency, but if I run arecord and stream >> video, then it is suddenly OK to change the frequency. > > How are you changing frequency? I want to duplicate what you are doing. v4l2-ctl -f > >> >> BTW, I think there was also inconsistent behavior in the order of streaming >> audio and video: if I stream video first, then I can stream audio afterwards. >> But if I stream audio first, then (if I remember correctly) I can't start >> video streaming. >> > > I will run some tests tomorrow and see what I find. Which video apps are > you running for these tests? v4l2-ctl or qv4l2. Regards, Hans > > thanks, > -- Shuah > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Verkuil Subject: Re: [PATCH v10 0/4] Media Device Allocator API Date: Wed, 30 Jan 2019 08:42:17 +0100 Message-ID: References: <481787e7-112a-80dd-228c-2497a12547b9@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from lb3-smtp-cloud7.xs4all.net (lb3-smtp-cloud7.xs4all.net [194.109.24.31]) by alsa0.perex.cz (Postfix) with ESMTP id DA5812666B3 for ; Wed, 30 Jan 2019 08:42:22 +0100 (CET) In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: shuah , mchehab@kernel.org, perex@perex.cz, tiwai@suse.com Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org List-Id: alsa-devel@alsa-project.org On 1/30/19 2:50 AM, shuah wrote: > On 1/29/19 2:43 AM, Hans Verkuil wrote: >> On 1/29/19 12:48 AM, shuah wrote: >>> Hi Hans, >>> >>> On 1/28/19 5:03 AM, Hans Verkuil wrote: >>>> Hi Shuah, >>>> >>>> On 1/24/19 9:32 PM, Shuah Khan wrote: >>>>> 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. >>>>> >>>>> - This patch series is tested on 5.0-rc3 and addresses comments on >>>>> v9 series from Hans Verkuil. >>>>> - v9 was tested on 4.20-rc6. >>>>> - Tested sharing resources with kaffeine, vlc, xawtv, tvtime, and >>>>> arecord. When analog is streaming, digital and audio user-space >>>>> applications detect that the tuner is busy and exit. When digital >>>>> is streaming, analog and audio applications detect that the tuner is >>>>> busy and exit. When arecord is owns the tuner, digital and analog >>>>> detect that the tuner is busy and exit. >>>> >>>> I've been doing some testing with my au0828, and I am confused about one >>>> thing, probably because it has been too long ago since I last looked into >>>> this in detail: >>>> >>> >>> Great. >>> >>>> Why can't I change the tuner frequency if arecord (and only arecord) is >>>> streaming audio? If arecord is streaming, then it is recording the audio >>>> from the analog TV tuner, right? So changing the analog TV frequency >>>> should be fine. >>>> >>> >>> Changing analog TV frequency would be s_frequency. The way it works is >>> any s_* calls would require holding the pipeline. In Analog TV case, it >>> would mean holding both audio and video pipelines for any changes >>> including TV. >>> >>> As I recall, we discussed this design and the decision was to make all >>> s_* calls interfaces to hold the tuner. A special exception is g_tuner >>> in case of au0828. au0828 initializes the tuner from s_* interfaces and >>> its g_tuner interfaces. Allowing s_frequency to proceed will disrupt the >>> arecord audio stream. >>> >>> Query (q_*) works just fine without holding the pipeline. I limited the >>> analog holds to just the ones that are required. The current set is >>> required to avoid audio stream disruptions. >> >> So I am not sure about that ('avoid audio stream disruptions'): if I >> stream video AND use arecord, then I can just set the frequency while >> streaming. Doesn't that interrupt audio as well? And are you sure changing >> the tuner frequency actually disrupts audio? And if audio is disrupted, >> are we talking about a glitch or is audio permanently disrupted? > > I think it is a glitch. I will run some tests and let you know. >> >> That's basically the inconsistent behavior I noticed: just running arecord >> will prevent me from changing the frequency, but if I run arecord and stream >> video, then it is suddenly OK to change the frequency. > > How are you changing frequency? I want to duplicate what you are doing. v4l2-ctl -f > >> >> BTW, I think there was also inconsistent behavior in the order of streaming >> audio and video: if I stream video first, then I can stream audio afterwards. >> But if I stream audio first, then (if I remember correctly) I can't start >> video streaming. >> > > I will run some tests tomorrow and see what I find. Which video apps are > you running for these tests? v4l2-ctl or qv4l2. Regards, Hans > > thanks, > -- Shuah >