Steinberg UR22 Crackling and Clicks

[Kilian]

>> > Then try to pass implicit_fb=1 option to snd-usb-audio module.
>> > It's a new option that was added recently.
>> >
>> >
>> > Takashi
>> 
>> Nice, that did the trick. there was a small glitch on first playback
>> but I can not reproduce it now. Playback seems glitch-free now. I will
>> test it with pulseaudio in the gui if I can. It's not quite easy to
>> test, because the system locks up after a while with the new kernel
>> and gnome 3. I will also test concurrent playback and recording,
>> too. Thank you very much, that was a huge help!
> 
> Good to hear.  If the implicit_fb option works, we can add a static
> quirk table entry easily.  Just add IMPLICIT_FB_GENERIC_DEV() with the
> device ID to playback_implicit_fb_quirks[] table in
> sound/usb/implicit.c.
> 
> 
> Takashi

Still having problems with the nouveau driver, so i couldn't thest this 
with pulseaudio. Recording with arecord works parallel to playing back 
with aplay. so here is my patch for implicit.c

diff --git a/sound/usb/implicit.c b/sound/usb/implicit.c
index 386198b36b87..c729ff634b9d 100644
--- a/sound/usb/implicit.c
+++ b/sound/usb/implicit.c
@@ -46,6 +46,7 @@ static const struct snd_usb_implicit_fb_match 
playback_implicit_fb_quirks[] = {
         IMPLICIT_FB_GENERIC_DEV(0x0763, 0x2081), /* M-Audio FastTrack 
Ultra */
         IMPLICIT_FB_GENERIC_DEV(0x0763, 0x2030), /* M-Audio Fast Track 
C400 */
         IMPLICIT_FB_GENERIC_DEV(0x0763, 0x2031), /* M-Audio Fast Track 
C600 */
+       IMPLICIT_FB_GENERIC_DEV(0x0499, 0x1509), /* Steinberg UR22 */

         /* Fixed EP */
         /* FIXME: check the availability of generic matching */