On Tue, 18 Oct 2016 15:33:42 +0200, Felipe Ferreri Tonello wrote: > > Hi Takashi > > On 18/10/16 13:07, Takashi Iwai wrote: > > On Wed, 12 Oct 2016 18:15:04 +0200, > > Bastien Nocera wrote: > >> > >> On Wed, 2016-10-12 at 18:06 +0200, Clemens Ladisch wrote: > >>> 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. > >> > >> I'm guessing it doesn't support it then (see attached log) > > > > So this looks like a HID, not from the audio device class. > > It's an oft-seen implementation. > > > >> I also checked the input device output when plugging in something, with > >> evtest, and no feedback either. > > > > Then at first you need to hack a HID driver to support this device. > > It'll create an input device, and then we'll need to find some way to > > couple the given input device and the audio device. We can parse the > > sysfs device path to figure out, but I'm not sure what's the best way > > to tell it to applications. > > > > Why not use similar API as a normal ALSA card? This will enable jack > detection by default in applications using kcontrol interface. Are you suggesting to create another sound card object by a HID driver? This would be even less useful. Then you'll have two individual sound cards in the end that have no connection between them. Takashi -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
