Assertion elem failed - simple.c:914

[JCruk]

I am trying to get set up with a Scarlett 18i20 on Ubuntu 20.04 and successfully compiled the latest scarlett-mixer. But, when I launch ./scarlett-mixer as my user or with sudo I get an assertion elem error:

user@system:~/$ ./scarlett-mixer 
scarlett-mixer: simple.c:914: snd_mixer_selem_get_enum_items: Assertion `elem' failed.
Aborted (core dumped)

user@system:~/$ sudo ./scarlett-mixer 
scarlett-mixer: simple.c:914: snd_mixer_selem_get_enum_items: Assertion `(elem)->type == SND_MIXER_ELEM_SIMPLE' failed.
Aborted

Could this be due to something I'm doing wrong in running the compiled binary or how I've compiled it?

[x42]

Are you using a 1st generation Scarlett device?
If not, this is likely the same as #16

[x42]

The output of ./scarlett-mixer -vv --print-controls may be helpful if someone were to add support for other devices.

[lazzarello]

Same for me but with a 18i8 on the same version of Ubuntu. My guess is it's the empty elements in the out_gain_labels array? This is my first time looking at this output tho 🤷

lee@henry:~/src/bela/scarlett-mixer$ ./scarlett-mixer -vv --print-controls
* hw:0 "HDA Intel PCH"
* hw:1 "HDA NVidia"
* hw:2 "Display Audio"
* hw:3 "Bela"
* hw:4 "Scarlett 18i8 USB"
Autodetect: Using "hw:4"
Device `Scarlett 18i8 USB' has 1 contols: 
 0 'Clock Source Clock Source', ENUM
CMP 18
--- Device: Scarlett 18i8 USB
Matrix: in=0, out=0, off=0, stride=0
Matrix: input-select=0, select-stride=0
Inputs: ins=0 select-offset=0
Masters: n_mst=0 n_out-select=0
Switches: n_pad=0, n_hiz=0
hiz_map = {-1, -1, };
pad_map = {-1, -1, -1, -1, };
out_gain_map = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, };
out_gain_labels = {, , , , , , , , , , };
out_bus_map = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, };
---
--- Device: Scarlett 18i8 USB
Matrix: in=18, out=8, off=40, stride=9
Matrix: input-select=39, select-stride=9
Inputs: ins=18 select-offset=20
Masters: n_mst=4 n_out-select=8
Switches: n_pad=4, n_hiz=2
hiz_map = {15, 17, };
pad_map = {16, 18, 19, 20, };
out_gain_map = {1, 4, 7, 10, -1, -1, -1, -1, -1, -1, };
out_gain_labels = {Monitor, Headphone 1, Headphone 2, SPDIF, , , , , , , };
out_bus_map = {2, 3, 5, 6, 8, 9, 11, 12, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, };
---
scarlett-mixer: simple.c:914: snd_mixer_selem_get_enum_items: Assertion `(elem)->type == SND_MIXER_ELEM_SIMPLE' failed.
Aborted (core dumped)

[lazzarello]

Confirmed it's not the same as #16

I have a Gen2 as reported by the driver but the USB Product ID is different. It says it is a

[Thu Jul 30 01:05:08 2020] usb 1-1.3: new high-speed USB device number 8 using ehci-pci
[Thu Jul 30 01:05:08 2020] usb 1-1.3: New USB device found, idVendor=1235, idProduct=8204, bcdDevice= 4.34
[Thu Jul 30 01:05:08 2020] usb 1-1.3: New USB device strings: Mfr=1, Product=3, SerialNumber=2
[Thu Jul 30 01:05:08 2020] usb 1-1.3: Product: Scarlett 18i8 USB
[Thu Jul 30 01:05:08 2020] usb 1-1.3: Manufacturer: Focusrite
[Thu Jul 30 01:05:08 2020] usb 1-1.3: SerialNumber: 00033431
[Thu Jul 30 01:05:08 2020] usb 1-1.3: Focusrite Scarlett Gen 2 Mixer Driver disabled; use options snd_usb_audio device_setup=1 to enable and report any issues to [email protected]

I added options snd_usb_audio vid=0x1235 pid=0x8204 device_setup=1 to /etc/modprobe.d/scarlett.conf

And I got an error message, which I assume is something caused by the module options not being applied as intended?

[Thu Jul 30 01:16:15 2020] usb 1-1.3: Scarlett Gen 2 USB response result cmd 0 was -110
[Thu Jul 30 01:16:15 2020] snd-usb-audio: probe of 1-1.3:1.0 failed with error -22

Might be time to email g at b4.vu ? I'll look at the source for this too. The segfault seems like it would be trying to access array elements past its length, right?

If it helps, kernel version/module path

filename:       /lib/modules/5.4.0-42-generic/kernel/sound/usb/snd-usb-audio.ko
license:        GPL
description:    USB Audio
author:         Takashi Iwai <[email protected]>
srcversion:     47C947C0C803DEC837E7FAB

Full kernel string is Linux henry 5.4.0-42-generic #46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

[lazzarello]

Whelp, I emailed the author of the driver and we determined that my problem is the same as #16 . But an unrelated problem was my driver wouldn't load with the mixer option because the hub it was attached to is inside an Apple Thunderbolt 2 display, connected to a Thunderbolt 3 adapter, connected to the USB-C port of a Thinkpad. That's a mouthful but somehow it doesn't work with this device.

I don't think it's a bandwidth problem since the same hub attached to a Macbook Pro without the hardware adapter works as expected. So yeah...hardware problem. Everything is fine.

[x42]

according to #16 (comment) it works after the driver is force loaded.

[lazzarello]

Yeah, it works with the device_setup=1 option. The GUI isn't mapping parameters correctly for the mixer matrix. That might be a thing I can fix. I think this issue could be closed since the driver needs that option for > Gen1 devices, which is specified in that issue with more detail.