From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755969AbcB0Czq (ORCPT ); Fri, 26 Feb 2016 21:55:46 -0500 Received: from lists.s-osg.org ([54.187.51.154]:45714 "EHLO lists.s-osg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755533AbcB0Czo (ORCPT ); Fri, 26 Feb 2016 21:55:44 -0500 Subject: Re: [PATCH v3 22/22] sound/usb: Use Media Controller API to share media resources To: Takashi Iwai References: <0822f80e0acc5119e6f6deccf002ccadeb3b145b.1455233156.git.shuahkh@osg.samsung.com> <56D0B0CB.8060709@osg.samsung.com> Cc: hans.verkuil@cisco.com, laurent.pinchart@ideasonboard.com, clemens@ladisch.de, sakari.ailus@linux.intel.com, javier@osg.samsung.com, mchehab@osg.samsung.com, geliangtang@163.com, alsa-devel@alsa-project.org, arnd@arndb.de, ricard.wanderlof@axis.com, labbott@fedoraproject.org, chehabrafael@gmail.com, klock.android@gmail.com, misterpib@gmail.com, prabhakar.csengg@gmail.com, ricardo.ribalda@gmail.com, ruchandani.tina@gmail.com, takamichiho@gmail.com, tvboxspy@gmail.com, dominic.sacre@gmx.de, albert@huitsing.nl, crope@iki.fi, julian@jusst.de, pierre-louis.bossart@linux.intel.com, corbet@lwn.net, joe@oampo.co.uk, johan@oljud.se, dan.carpenter@oracle.com, pawel@osciak.com, p.zabel@pengutronix.de, perex@perex.cz, stefanr@s5r6.in-berlin.de, inki.dae@samsung.com, j.anaszewski@samsung.com, jh1009.sung@samsung.com, k.kozlowski@samsung.com, kyungmin.park@samsung.com, m.szyprowski@samsung.com, nenggun.kim@samsung.com, sw0312.kim@samsung.com, elfring@users.sourceforge.net, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linuxbugs@vittgam.net, gtmkramer@xs4all.nl, normalperson@yhbt.net, daniel@zonque.org, Shuah Khan From: Shuah Khan Organization: Samsung Open Source Group Message-ID: <56D1102B.8060501@osg.samsung.com> Date: Fri, 26 Feb 2016 19:55:39 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/26/2016 01:50 PM, Takashi Iwai wrote: > On Fri, 26 Feb 2016 21:08:43 +0100, > Shuah Khan wrote: >> >> On 02/26/2016 12:55 PM, Takashi Iwai wrote: >>> On Fri, 12 Feb 2016 00:41:38 +0100, >>> Shuah Khan wrote: >>>> >>>> Change ALSA driver to use Media Controller API to >>>> share media resources with DVB and V4L2 drivers >>>> on a AU0828 media device. 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 | 318 +++++++++++++++++++++++++++++++++++++++++++++++ >>>> sound/usb/media.h | 72 +++++++++++ >>>> sound/usb/mixer.h | 3 + >>>> sound/usb/pcm.c | 28 ++++- >>>> sound/usb/quirks-table.h | 1 + >>>> sound/usb/stream.c | 2 + >>>> sound/usb/usbaudio.h | 6 + >>>> 11 files changed, 448 insertions(+), 5 deletions(-) >>>> create mode 100644 sound/usb/media.c >>>> create mode 100644 sound/usb/media.h >>>> >>>> diff --git a/sound/usb/Kconfig b/sound/usb/Kconfig >>>> index a452ad7..ba117f5 100644 >>>> --- a/sound/usb/Kconfig >>>> +++ b/sound/usb/Kconfig >>>> @@ -15,6 +15,7 @@ config SND_USB_AUDIO >>>> select SND_RAWMIDI >>>> select SND_PCM >>>> select BITREVERSE >>>> + select SND_USB_AUDIO_USE_MEDIA_CONTROLLER if MEDIA_CONTROLLER && MEDIA_SUPPORT >>> >>> Looking at the media Kconfig again, this would be broken if >>> MEDIA_SUPPORT=m and SND_USB_AUDIO=y. The ugly workaround is something >>> like: >>> select SND_USB_AUDIO_USE_MEDIA_CONTROLLER \ >>> if MEDIA_CONTROLLER && (MEDIA_SUPPORT=y || MEDIA_SUPPORT=SND) >> >> My current config is MEDIA_SUPPORT=m and SND_USB_AUDIO=y >> It is working and I didn't see any issues so far. > > Hmm, how does it be? In drivers/media/Makefile: > > ifeq ($(CONFIG_MEDIA_CONTROLLER),y) > obj-$(CONFIG_MEDIA_SUPPORT) += media.o > endif > > So it's a module. Meanwhile you have reference from usb-audio driver > that is built-in kernel. How is the symbol resolved? Sorry my mistake. I misspoke. My config had: CONFIG_MEDIA_SUPPORT=m CONFIG_MEDIA_CONTROLLER=y CONFIG_SND_USB_AUDIO=m The following doesn't work as you pointed out. CONFIG_MEDIA_SUPPORT=m CONFIG_MEDIA_CONTROLLER=y CONFIG_SND_USB_AUDIO=y okay here is what will work for all of the possible combinations of CONFIG_MEDIA_SUPPORT and CONFIG_SND_USB_AUDIO select SND_USB_AUDIO_USE_MEDIA_CONTROLLER \ if MEDIA_CONTROLLER && ((MEDIA_SUPPORT=y) || (MEDIA_SUPPORT=m && SND_USB_AUDIO=m)) The above will cover the cases when 1. CONFIG_MEDIA_SUPPORT and CONFIG_SND_USB_AUDIO are both modules CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER is selected 2. CONFIG_MEDIA_SUPPORT=y and CONFIG_SND_USB_AUDIO=m CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER is selected 3. CONFIG_MEDIA_SUPPORT=y and CONFIG_SND_USB_AUDIO=y CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER is selected 4. CONFIG_MEDIA_SUPPORT=m and CONFIG_SND_USB_AUDIO=y This is when we don't want CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER selected I verified all of the above combinations to make sure the logic works. If you think of a better way to do this please let me know. I will go ahead and send patch v4 with the above change and you can decide if that is acceptable. >>> >>> Other than that, it looks more or less OK to me. >>> The way how media_stream_init() gets called is a bit worrisome, but it >>> should work practically. Another concern is about the disconnection. >>> Can all function calls in media_device_delete() be safe even if it's >>> called while the application still opens the MC device? >> >> Right. I have been looking into device removal path when >> ioctls are active and I can resolve any issues that might >> surface while an audio app is active when device is removed. > > So, it's 100% safe to call all these media_*() functions while the > device is being accessed before closing? > There is a known problem with device removal when media device file is open and ioctl is in progress. This isn't specific to this patch series, a general problem that is related to media device removal in general. I am working on a fix for this problem. As you said, earlier, I can work on fixing issues after the merge. thanks, -- Shuah -- Shuah Khan Sr. Linux Kernel Developer Open Source Innovation Group Samsung Research America (Silicon Valley) shuahkh@osg.samsung.com | (970) 217-8978