Hi Geraldo,
Have you tried unloading the snd-usb-audio module and the reloading it
with implicit_fb=1 as in "modprobe -r snd-usb-audio" and "modprobe
snd-usb-audio implicit_fb=1" ?
If not, try it. If it works and your playback issues are gone then
your device may just need a quirk. If it doesn't work we still
have dyndbg to go through.
It works! Had to switch the devices and options back and forth in
pavucontrol
(sometimes needed even for the choppy playback), but it works.
So why did my quirks didn't work? Maybe I gave the wrong numbers? Or the
code
was unreachable (I didn't put printk()s, sorry). I guessed the combos from
`lsusb -v` output, and even tried the combos that didn't make any sense
(because I didn't know what I was doing).
Here's what I tried, one after another (added to
playback_implicit_fb_quirks in
/sound/usb/implicit.c):
IMPLICIT_FB_GENERIC_DEV(0x1397, 0x0507),
/* Didn't work */
IMPLICIT_FB_FIXED_DEV(0x1397, 0x0507, 0x84, 1),
/* Interface 2 is actually Capture as per `cat /proc/asound/card1/stream0`,
* but "Implicit feedback Data" is found under that
* (Interface 1 has explicit Feedback), and a Scarlett quirk seemed to use
* a capture interface in playback_implicit_fb_quirks
* (I know that it's a capture interface from `lsusb` output posted by
someone
* online)
*/
/* Didn't work */
IMPLICIT_FB_FIXED_DEV(0x1397, 0x0507, 0x88, 2),
/* Didn't work */
/* What am I doing with 0x08 ? */
IMPLICIT_FB_FIXED_DEV(0x1397, 0x0507, 0x08, 1),
/* Didn't work */
/* Why BOTH? But what's FIXED at first? Didn't find any doc. */
IMPLICIT_FB_BOTH_DEV(0x1397, 0x0507, 0x84, 1),
/* Didn't work */
IMPLICIT_FB_SKIP_DEV(0x1397, 0x0507),
Last but not least, please use a vanilla kernel for these tests.
I built it using the source from kernel.org, not apt. But I've used
oldconfig,
and I think patches are being applied while installing the kernel
(currently I'm
using my daily driver installation for this). If it has to be more pure,
I 'll
try. BTW, do you have any distro to recommend that has a near-vanilla
kernel for
experiments like this?
Another question: assuming a quirk gets added for this device, is there any
chance that the quirk would break the experience for those who are already
using the device (possibly a different revision, but the same ID [1])
without
any issues?
[1] https://h-node.org/soundcards/view/en/2228/Behringer-UMC202HD
Thank you,
--
Nandakumar Edamana
https://nandakumar.org
GPG Key: https://nandakumar.org/contact/gpgkey.asc
GPG Key Fingerprint: BA6B 8FDE 644F F861 B638 3E2F 45D6 05FC 646A F75D
