Behringer UMC202HD issues and a partial solution

[Geraldo Nascimento]

On Tue, Jan 18, 2022 at 04:50:12PM +0530, Nandakumar Edamana wrote:
> 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.

Yes, it will install on extra/ if you are building with the M=sound/usb
option. I guess the 'official' solution is to use the INSTALL_MOD_PATH
environment variable.

But what I do instead is I overwrite
/lib/modules/<kernel_version>/kernel/sound/usb/snd-usb-audio.ko with the newly
built one, and then I run depmod.

> 
> 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).

I noticed that on your dmesg logs, that the warning was nowhere to be
found.

Thank you,
Geraldo Nascimento

> 
> -- 
> Nandakumar Edamana
> https://nandakumar.org
>