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blacklight

Member

Registered: 2016-04-06

Posts: 4

[SOLVED] Multiple USB soundcards setup failures

I have a Dell XPS 13 9343 with the following default soundcards configuration:

$ cat /proc/asound/cards
 0 [PCH            ]: HDA-Intel - HDA Intel PCH
                      HDA Intel PCH at 0xf7218000 irq 48
 1 [HDMI           ]: HDA-Intel - HDA Intel HDMI
                      HDA Intel HDMI at 0xf721c000 irq 51

I also sometimes add either an external USB soundcard or a MIDI keyboard for recording. Adding only one of them works flawlessly.

However, when I try to plug both only one of them is recognized. journalctl -xe shows the following lines when the cable is plugged in:

May 07 18:09:08 volta kernel: usb 2-2.4: new full-speed USB device number 14 using xhci_hcd
May 07 18:09:08 volta kernel: usb 2-2.4: New USB device found, idVendor=2702, idProduct=2702, bcdDevice= 1.00
May 07 18:09:08 volta kernel: usb 2-2.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0
May 07 18:09:08 volta kernel: usb 2-2.4: Product: CME M-Key
May 07 18:09:08 volta kernel: usb 2-2.4: Manufacturer: CME
May 07 18:09:08 volta kernel: snd-usb-audio 2-2.4:1.0: cannot find the slot for index 1 (range 0-2), error: -16
May 07 18:09:08 volta kernel: usb 2-2.4: cannot create card instance 1

It seems to me that for some reason the soundcard space is limited to a 0-2 range, and it won't support adding another soundcard.

Since I haven't found much documentation online about this specific error I'd like to know:

* Is this a known ALSA or snd-usb-audio design limitation?
* If so, is there a way to override it?

Last edited by blacklight (2019-05-07 23:07:53)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,237

Re: [SOLVED] Multiple USB soundcards setup failures

Sounds like incorrect modprobe configuration. Any files there? What are their contents?

blacklight

Member

Registered: 2016-04-06

Posts: 4

Re: [SOLVED] Multiple USB soundcards setup failures

Thanks for the hint @V1del. It seemed indeed a modprobe configuration issue. I've now taken a look at the multiple USB devices configuration section on the ALSA docs to statically configure the device indexes based on module and vendor ID and for now it seems to work with this configuration:

alias snd-card-0 snd-hda-intel
alias snd-card-1 snd-hda-intel
alias snd-card-2 snd-usb-audio
alias snd-card-3 snd-virmidi

options snd cards_limit=4
options snd-hda-intel index=1,0
options snd-usb-audio index=2,1 vid=0x1235,0x8202
options snd-virmidi index=3 vid=0x2702,0x2702
blacklist snd_hda_codec_hdmi

Last edited by blacklight (2019-05-07 23:07:34)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,237

Re: [SOLVED] Multiple USB soundcards setup failures

That reads unnecessarily convoluted, and if you ever plug the device with vid 0x8202 you will once again have a index race with your snd-hda-intel card.

Either don't configure the indices at all or configure them so that your device are assigned uniquely.