Behringer UMC202HD issues and a partial solution

[Nandakumar Edamana]

I feel like I'm doing something wrong with the build and install 
process. Maybe it's been the case for the last couple of days, in which 
case I'm terribly sorry for the incorrect test results.

The problem is, I don't get any printk() outputs at all. I'd given `echo 
"7" > /proc/sys/kernel/printk`, and I even added a usb_audio_dbg() line, 
which didn't get printed either.

Then I saw this:

$ find /lib/modules/ -name 'snd-usb-audio.ko'|xargs ls
...
/lib/modules/5.15.13/extra/usb/snd-usb-audio.ko
/lib/modules/5.15.13/kernel/sound/usb/snd-usb-audio.ko
...

modprobe is using the kernel/ version while my commands were installing 
the extra/ version.

Then I used the following, which also installed the extra/ version:
sudo make -C /lib/modules/5.15.13/build M=sound modules_install

Are these two versions supposed to exist? What is the solution? Telling 
the kernel build system to choose the correct location or configuring 
modprobe or depmod or something? I tried to look it up, but didn't find 
any official recommendation.

Anyway, I ran this:

# Because I have space constraints
# find /lib/modules/5.15.13/ -name '*.ko' -exec strip --strip-unneeded {} +
# update-initramfs -u -k 5.15.13

That updated the extra/ version of snd-usb-audio. But even after a 
reboot, this is what I get:

# modprobe -r -v snd-usb-audio
rmmod snd_usb_audio
rmmod snd_usbmidi_lib
# modprobe -v snd_usb_audio dyndbg==p
insmod /lib/modules/5.15.13/kernel/sound/usb/snd-usbmidi-lib.ko
insmod /lib/modules/5.15.13/kernel/sound/usb/snd-usb-audio.ko index=-2 
index=-2 index=-2 dyndbg==p
# dmesg |grep 'implicit:'

Another thing is, even though I'd commented out my clock workaround, I'm 
not getting any clock-related warning at all (I'm sure those went away 
after I edited clock.c, and then performed a build+install).

-- 
Nandakumar Edamana
https://nandakumar.org