[alsa-devel] Jack sensing in snd_usb_audio ?

[Clemens Ladisch]

Bastien Nocera wrote:
> On Wed, 2016-10-12 at 14:43 +0200, Clemens Ladisch wrote:
>> Bastien Nocera wrote:
>>> "
>>> A change of state in the audio function is most often caused by a
>>> certain event that takes place. An event can either be user-
>>> initiated
>>> or device-initiated. User-initiated jack insertion or removal is a
>>> typical example of a user-initiated event.
>>> "
>>
>> There are not many USB Audio 2.0 devices, and I'm not aware of any
>> that actually implements this.
>
> I guess I would see whether there are events if I captured the USB
> traffic even without special handling/turning on a feature in the
> drivers, right?

Most devices do not even have the status endpoint (see "lsusb -v").
To check what events arrive, you can add logging to the
snd_usb_mixer_interrupt() function.


Regards,
Clemens