15 Sep
2013
15 Sep
'13
10:49 a.m.
Alan Stern wrote:
On Sat, 14 Sep 2013, Clemens Ladisch wrote:
Alan Stern wrote:
So here's my question: If the sound driver recognizes that interface B is connected with interface A when B is probed, why can't it recognize this fact when A is probed? It could claim B while A's probe is running. Then the sound card would be registered with the PCM component already in place.
The sound driver already does this.
It does? Why does the comment preceding snd_usb_audio_probe() say:
- thus we check the usb device pointer and creates the card instance
- only at the first time. the successive calls of this function will
- append the pcm interface to the corresponding card.
For UAC devices with correct descriptors, and for devices with multi- interface quirks, the driver claims all interfaces at once. But it is still possible to have devices with zero or two audio control interfaces.
Regards, Clemens