From: Shuah Khan Subject: Re: [alsa-devel] Linux 4.2 ALSA snd-usb-audio inconsistent lock state warn in PCM nonatomic mode Date: Wed, 2 Sep 2015 08:54:15 -0600 Message-ID: <55E70D97.1010206@osg.samsung.com> References: <55E4D9BE.2040308@osg.samsung.com> <55E564ED.4050609@ladisch.de> <55E5E31F.6040802@osg.samsung.com> <55E5E625.5010403@ladisch.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55E5E625.5010403@ladisch.de> Sender: linux-media-owner@vger.kernel.org To: Clemens Ladisch Cc: alsa-devel@alsa-project.org, linux-media@vger.kernel.org, Shuah Khan List-Id: alsa-devel@alsa-project.org On 09/01/2015 11:53 AM, Clemens Ladisch wrote: > Shuah Khan wrote:> On 09/01/2015 02:42 AM, Clemens Ladisch wrote: >>> Shuah Khan wrote: >>>> +++ b/sound/usb/stream.c >>>> pcm->private_data = as; >>>> pcm->private_free = snd_usb_audio_pcm_free; >>>> pcm->info_flags = 0; >>>> + pcm->nonatomic = true; >>> >>> Why do you think you need nonatomic mode in the USB audio driver? >> >> I have been working on adding Media Controller support for this chip >> as chip specific feature in ALSA. This will allow sharing resources >> such as the tuner across the drivers that control the device (DVB, >> Video, snd-usb-audio). Media Controller framework uses a mutex to >> protect access to resources, hence there is a need to hold this mutex >> from SNDRV_PCM_TRIGGER_START and SNDRV_PCM_TRIGGER_STOP which could run >> in IRQ context. > > Resources should be managed in the hw_params/hw_free callbacks. > snd_usb_hw_params() and snd_usb_hw_free() are the two places I could add resource access logic and try if that works for what I am trying to do. Thanks for the tip. thanks, -- Shuah -- Shuah Khan Sr. Linux Kernel Developer Open Source Innovation Group Samsung Research America (Silicon Valley) shuahkh@osg.samsung.com | (970) 217-8978