[alsa-devel] Fwd: [BUG] The infamous MOTU Ultralite * bitcrunch issue

[Stanisław Drozd]

[Originally posted in alsa-user, but that list doesn't appear to be very widely used]
Hello everyone,
I recently updated the firmware on my UltraLite mk4 (IF YOURS IS WORKING OK, DON'T UPGRADE or you'll repeat my mistake). Current firmware on my piece is 1.3.4+232, 07/27/18 17:46:22, BIOS is Aug-04-2017 b568a4c.

After the update an issue appeared - a moment after initializing the device and playing normally, it starts sounding as if it was put through a bitcruncher effect. After a longer while the output loses gain only to disappear completely after some more seconds pass (the gain change is not smooth, it seems to go away in steps).

What I have tried:
* Switching internal clock to LTC on the interface - would hold the sync together for a little longer; I did NOT send the actual timecode because I had trouble finding something to generate it for me
* Switching sample rates - No noticeable change in behavior
* Testing with speaker-test - No change in behavior, looks like this has to happen on ALSA level or lower
* Changing clock source in Cadence (a JACK helper) settings and reinitializing - No effect

Possible clues I saw:
* dmesg started showing this when I plug the device in:
[  533.419099] usb 1-2.3: new high-speed USB device number 8 using xhci_hcd
[  533.527638] usb 1-2.3: New USB device found, idVendor=07fd, idProduct=0005, bcdDevice= 2.00
[  533.527646] usb 1-2.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  533.527650] usb 1-2.3: Product: UltraLite-mk4
[  533.527654] usb 1-2.3: Manufacturer: MOTU
[  533.527658] usb 1-2.3: SerialNumber: 0001f2fffe008e19
[  534.377873] usb 1-2.3: clock source 1 is not valid, cannot use
<and about 50 more lines of the clock source message>

Questions:
* What other places can I go to to report this?
* What other settings can I tweak?

Thanks,
Stanislaw

PS: I have a basic understanding of driver work, I think I could help with creating a patch with some guidance