Bug 208851

Summary: Steinberg UR22C: Crackling Audio
Product: Drivers Reporter: Joshua Sivec (joshua.sivec)
Component: Sound(ALSA)Assignee: Jaroslav Kysela (perex)
Status: RESOLVED CODE_FIX    
Severity: normal CC: tiwai
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 5.8.0+ Subsystem:
Regression: No Bisected commit-id:
Attachments: alsa-info.sh output
Add implicit feedback quirk

Description Joshua Sivec 2020-08-09 13:17:08 UTC 
Created attachment 290811 [details]
alsa-info.sh output

The UR22C produces a crackling / pop noise once every while.

speaker-test -t sine at 48kHz produces one once every ~35 second.

It seems to require a implicit feedback quirk in /sounds/usb/pcm.c, lsusb -v -d 0499:172f also shows "Implicit feedback Data".

I simply added the following patch to the MOTU M & SSL2, since they have the same endpoint, this fixes the crackling / pop issue:

    case USB_ID(0x31e9, 0x0002): /* Solid State Logic SSL2+ */
+   case USB_ID(0x0499, 0x172f): /* Steinberg UR22C */
    case USB_ID(0x0d9a, 0x00df): /* RTX6001 */


However, duplex audio is not working with Pulseaudio anymore, similar to bug 207023. Jack works fine in duplex mode.

- Attached is the output of alsa-info.sh before the patch was applied.
- BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207023
Comment 1 Joshua Sivec 2020-08-09 13:33:39 UTC 
Created attachment 290813 [details]
Add implicit feedback quirk

Attached is the patch, which simply adds the implicit feedback quirk (same as in the main post).
Comment 2 Takashi Iwai 2020-12-08 12:59:07 UTC 
The fix was merged in 5.9 kernel.