Ubuntu build instructions

[alamminsalo]

Any possibility to get this working on Ubuntu?
I almost got it to work by cloning linux sources (v5.4) and including sound/usb/{midi.h, usbaudio.h} from there.
I'm unsure if doing this correctly (not much C-background). It seems to compile and when loaded recognizes digitakt. However there is some issue when trying to start jack with it and atleast with lowlatency kernel I had couple freezes when turning the device on/off.

[dagargo]

I tried to use it in Debian Buster (amd64) but I had some kernel freezes too with the standard kernel. Could you check if your issue is related to #1 ?

[alamminsalo]

I believe so, yes

[naught101]

It would still be good to add some instructions for ubuntu to the README. I haven't managed to get it to work yet. This is what I've tried:

• uname -a to get the kernel version, for me it's 5.4: 5.4.0-31-lowlatency #35-Ubuntu SMP PREEMPT Thu May 7 22:51:24 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
• go find the appropriate tag in the kernel source: https://github.com/torvalds/linux/releases/tag/v5.4, and open the commit, and browse files (https://github.com/torvalds/linux/tree/219d54332a09e8d8741c1e1982f5eae56099de85)
• Look in sound/usb and grab usbaudio.h and copy it to sound/usb/misc/from-kernel/ in the snd-digitakt repo (make the directory if it doesn't exists), or click the file, click "raw", and wget it (in my case wget https://raw.githubusercontent.com/torvalds/linux/219d54332a09e8d8741c1e1982f5eae56099de85/sound/usb/usbaudio.h)
  • Do the same for midi.h (wget https://raw.githubusercontent.com/torvalds/linux/219d54332a09e8d8741c1e1982f5eae56099de85/sound/usb/midi.h)
• From the sound/usb/misc dir, run make, which results in:

dpkg-query: no packages found matching raspberrypi-kernel-headers*
make -C /lib/modules/5.4.0-31-lowlatency/build M=/home/nedcr/Downloads/source_code/snd-digitakt/sound/usb/misc modules
make[1]: Entering directory '/usr/src/linux-headers-5.4.0-31-lowlatency'
dpkg-query: no packages found matching raspberrypi-kernel-headers*
  CC [M]  /home/nedcr/Downloads/source_code/snd-digitakt/sound/usb/misc/digitakt.o
  LD [M]  /home/nedcr/Downloads/source_code/snd-digitakt/sound/usb/misc/snd-digitakt.o
dpkg-query: no packages found matching raspberrypi-kernel-headers*
  Building modules, stage 2.
  MODPOST 1 modules
  CC [M]  /home/nedcr/Downloads/source_code/snd-digitakt/sound/usb/misc/snd-digitakt.mod.o
  LD [M]  /home/nedcr/Downloads/source_code/snd-digitakt/sound/usb/misc/snd-digitakt.ko
make[1]: Leaving directory '/usr/src/linux-headers-5.4.0-31-lowlatency'

the dpkg errors can be ignored, I think. This results in:

digitakt.c  from-kernel  modules.order   snd-digitakt.ko   snd-digitakt.mod.c  snd-digitakt.o
digitakt.o  Makefile     Module.symvers  snd-digitakt.mod  snd-digitakt.mod.o

• Run sudo make install, which results in:

dpkg-query: no packages found matching raspberrypi-kernel-headers*
make -C /lib/modules/5.4.0-31-lowlatency/build M=/home/nedcr/Downloads/source_code/snd-digitakt/sound/usb/misc modules
make[1]: Entering directory '/usr/src/linux-headers-5.4.0-31-lowlatency'
dpkg-query: no packages found matching raspberrypi-kernel-headers*
dpkg-query: no packages found matching raspberrypi-kernel-headers*
  Building modules, stage 2.
  MODPOST 1 modules
make[1]: Leaving directory '/usr/src/linux-headers-5.4.0-31-lowlatency'
make -C /lib/modules/5.4.0-31-lowlatency/build M=/home/nedcr/Downloads/source_code/snd-digitakt/sound/usb/misc modules_install
make[1]: Entering directory '/usr/src/linux-headers-5.4.0-31-lowlatency'
  INSTALL /home/nedcr/Downloads/source_code/snd-digitakt/sound/usb/misc/snd-digitakt.ko
At main.c:160:
- SSL error:02001002:system library:fopen:No such file or directory: ../crypto/bio/bss_file.c:69
- SSL error:2006D080:BIO routines:BIO_new_file:no such file: ../crypto/bio/bss_file.c:76
sign-file: certs/signing_key.pem: No such file or directory
  DEPMOD  5.4.0-31-lowlatency
Warning: modules_install: missing 'System.map' file. Skipping depmod.
make[1]: Leaving directory '/usr/src/linux-headers-5.4.0-31-lowlatency'
depmod

Again, I think the dpkg errors are irrelevant, but the SSL error isn't, and the install fails.

Also, direct insmod fails:

sudo insmod snd-digitakt.ko
insmod: ERROR: could not insert module snd-digitakt.ko: Unknown symbol in module

Any ideas?

[Noir-]

I'm not very deep into Linux Kernel development so feel free to correct me.
But I highly doubt that copying the header files would work. The header files are supposed to expose functionality which is present in the kernel. When you add headers from a different kernel version than you are running, the "promised" functionality from the copied headers is simply not available. The error message Unknown symbol in module indicates this.
Maybe you can investigate the issue like described in here: https://askubuntu.com/a/1163861/520956

If my deductions are correct, you need to compile and/or install a kernel version which is compatible to this headers.

I got similar problems in the beginning when I tried to compile it on Arch Linux. I gave up on this since I wanted to use this module on the Raspberry Pi anyway.

[naught101]

Mmm, that's why I copied the header files from the same version in git, but yes, maybe that's not enough.

The errors in dmesg are:

[584072.889789] snd_digitakt: Unknown symbol __snd_usbmidi_create (err -2)
[584072.890502] snd_digitakt: Unknown symbol snd_usbmidi_disconnect (err -2)

And they don't appear in the /proc/kallsyms

Ah! but they do after sudo modprobe snd_usbmidi_lib, and then I can insmod OK. Which I guess means that the module needs to define a dependency somehow?

[naught101]

Now alsamixer shows Elektron Digitakt as a soundcard, with no controls, which I guess is OK.

However, I can't see it as a device in the Cadence config, so I can't use it for JACK (not sure if that should be possible), nor does it appear in the outputs/inputs for PulseAudio.

It doesn't show in arecord -l, but it does in arecord -L, as:

usbstream:CARD=Digitakt
    Elektron Digitakt
    USB Stream Output

Trying direct ALSA recording with ffmpeg, as described at https://trac.ffmpeg.org/wiki/Capture/ALSA also fails:

ffmpeg -f alsa -i usbstream:CARD=Digitakt -t 30 blah.wav
ffmpeg version 4.2.2-1ubuntu1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-3ubuntu1)
  configuration: --prefix=/usr --extra-version=1ubuntu1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  WARNING: library configuration mismatch
  avcodec     configuration: --prefix=/usr --extra-version=1ubuntu1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared --enable-version3 --disable-doc --disable-programs --enable-libaribb24 --enable-liblensfun --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libtesseract --enable-libvo_amrwbenc
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
ALSA lib pcm_usb_stream.c:508:(_snd_pcm_usb_stream_open) Unknown field hint
[alsa @ 0x55eb2d2336c0] cannot open audio device usbstream:CARD=Digitakt (Invalid argument)
usbstream:CARD=Digitakt: Input/output error

So I guess something's not registering correctly. Might still be to do with mis-matching headers, I guess.

[naught101]

@droelfdroelf or @alamminsalo any chance you could re-open this? Would be useful to have an active issue for discussion.

[naught101]

Huh.. new firmware out today has class compliance... will test and see if it works.

[Noir-]

Yeah it works on Linux. But it's only the stereo sum which is pretty useless for the use cases most people have in mind when they want to use this driver.

[naught101]

Ah, yeah, bummer. Oh well, still TRIG+YES will be nice. I will keep trying with snd-digitakt when I have time.

[naught101]

OK, progress. When I last tried, I forgot to put th DT in overbridge mode, hence it not being recognised as an audio device. Now it does show, but I can't get it to work with Jack:

 /usr/bin/jackd -R -P 75 -d alsa -d hw:Digitakt -r 48000 -n 2 -p 256 -s &
[1] 10922
jackdmp 1.9.12                                                                                                                                                                                                                        
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2016 Grame.
Copyright 2016-2017 Filipe Coelho.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
no message buffer overruns
no message buffer overruns
no message buffer overruns
JACK server starting in realtime mode with priority 75
self-connect-mode is "Don't restrict self connect requests"
audio_reservation_init
Device reservation request with priority 2147483647 denied for "Audio1": org.freedesktop.DBus.Error.NoReply (Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, 
Failed to acquire device name : Audio1 error : Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broke
Audio device hw:Digitakt cannot be acquired...
Cannot initialize driver
JackServer::Open failed with -1
Failed to open server

[1]  + 10922 exit 255   /usr/bin/jackd -R -P 75 -d alsa -d hw:Digitakt -r 48000 -n 2 -p 256 -s

[Noir-]

Have you tried with arecord just to make sure that it's not an issue with jack?

[naught101]

I just get

$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: CX8200 Analog [CX8200 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Digitakt [Digitakt], device 0: Digitakt [Digitakt]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
$ arecord -D hw:1 blah.wav
arecord: main:830: audio open error: Device or resource busy

Other settings don't seem to make an impact. Also, just plugging the DT in with OB kills pulse audio, and after that, I tried changing the USB config to USB audio/midi with it plugged in, and it froze my system entirely (to the point where even the SysReq magic keys wouldn't work). I can't see anything useful in the logs for that, but maybe that's because I always have trouble figuring out how to find "just before last crash" events in the system logs :/

[droelfdroelf]

To let you guys know, it is not dead (yet ;), I am just super busy with work...