[alsa-devel] Linux 4.2 ALSA snd-usb-audio inconsistent lock state warn in PCM nonatomic mode

[Clemens Ladisch]

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.


Regards,
Clemens