Add support for optical output of Asus Xonar U3

[gertjanol]

Could you add support for enabling the optical output of the Asus Xonar U3 USB soundcard? If I'm not mistaken, this is a one line change:

diff -uprN -X linux-3.6.2.orig/ 
Documentation/dontdiff linux-3.6.2.orig/sound/usb/mixer_quirks.c ./linu 
x-3.6.2/sound/usb/mixer_quirks.c 
--- linux-3.6.2.orig/sound/usb/mixer_quirks.c   2012-10-12 
15:50:59.000000000 -0500 
+++ ./linux-3.6.2/sound/usb/mixer_quirks.c      2012-10-20 
09:35:34.273150950 -0500 
@@ -1065,6 +1065,7 @@ int snd_usb_mixer_apply_create_quirk(str

        case USB_ID(0x0b05, 0x1739): 
        case USB_ID(0x0b05, 0x1743): 
+       case USB_ID(0x0b05, 0x17a0): 
                err = snd_xonar_u1_controls_create(mixer); 
                break;

See http://www.mentby.com/Group/alsa-user/asus-xonar-u3-usb-optical-output-unsettable.html

[popcornmix]

Generally I'm not keen on pulling in out of tree patches. It causes a maintenance headache when switching to newer kernels, and could have undesirable consequences.

If this patch is correct, it should be sumbitted upstream. If it's accepted there, I'm more likely to cherry-pick it into current kernel.

[gertjanol]

Ah yes, I understand. In fact, it is submitted upstream and incorporated in 3.8. Is there an ETA for the precompiled RPI modules for 3.8, or should I try to recompile 3.6 myself with this patch included?

[popcornmix]

Prebuilt 3.8 is available and seems stable for me:
raspberrypi/linux#225

sudo BRANCH=next rpi-upate
should update to it.

[gertjanol]

Thanks, works like a charm! 3.8 seems stable, and my Xonar U3 is working flawlessly :).