How to make usb device id static?

Question

linux

Good day to all!
I put an mpd player and connected two external usb audio cards, I broadcast to each different music, but the problem is that I need certain music from certain channels, which is possible if I configure the machine and do not reboot, after rebooting the usb devices are swapped and I would like to fix this but can't find where to make
the device look through so:

#cat /proc/asound/cards
 0 [Codec          ]: H3_Audio_Codec - H3 Audio Codec
                      H3 Audio Codec
 1 [Device         ]: USB-Audio - USB PnP Sound Device
                      C-Media Electronics Inc. USB PnP Sound Device at usb-1c1b400.usb-1, full speed
 2 [Device_1       ]: USB-Audio - USB Audio Device
                      GeneralPlus USB Audio Device at usb-1c1d400.usb-1, full speed

the same as aplay -l Tell me
, please, can you somehow add something to the cards file to assign a serial number to a specific card?

Answer 1

After a long search, I came across an interesting file /etc/modprobe.d/alsa-base.conf
. For me, its contents were as follows:

options snd-usb-audio index=1
# autoloader aliases
install sound-slot-0 /sbin/modprobe snd-card-0
install sound-slot-1 /sbin/modprobe snd-card-1
install sound-slot-2 /sbin/modprobe snd-card-2
install sound-slot-3 /sbin/modprobe snd-card-3
install sound-slot-4 /sbin/modprobe snd-card-4
install sound-slot-5 /sbin/modprobe snd-card-5
install sound-slot-6 /sbin/modprobe snd-card-6
install sound-slot-7 /sbin/modprobe snd-card-7

# Cause optional modules to be loaded above generic modules
install snd /sbin/modprobe --ignore-install snd $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-ioctl32 ; /sbin/modprobe --quiet --use-blacklist snd-seq ; }
#
# Workaround at bug #499695 (reverted in Ubuntu see LP #319505)
install snd-pcm /sbin/modprobe --ignore-install snd-pcm $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-pcm-oss ; : ; }
install snd-mixer /sbin/modprobe --ignore-install snd-mixer $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-mixer-oss ; : ; }
install snd-seq /sbin/modprobe --ignore-install snd-seq $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; /sbin/modprobe --quiet --use-blacklist snd-seq-oss ; : ; }
#
install snd-rawmidi /sbin/modprobe --ignore-install snd-rawmidi $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; : ; }
# Cause optional modules to be loaded above sound card driver modules
install snd-emu10k1 /sbin/modprobe --ignore-install snd-emu10k1 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-emu10k1-synth ; }
install snd-via82xx /sbin/modprobe --ignore-install snd-via82xx $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq ; }

# Load saa7134-alsa instead of saa7134 (which gets dragged in by it anyway)
install saa7134 /sbin/modprobe --ignore-install saa7134 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist saa7134-alsa ; : ; }
# Prevent abnormal drivers from grabbing index 0
options bt87x index=-2
options cx88_alsa index=-2
options saa7134-alsa index=-2
options snd-atiixp-modem index=-2
options snd-intel8x0m index=-2
options snd-via82xx-modem index=-2
options snd-usb-audio index=-2
options snd-usb-caiaq index=-2
options snd-usb-ua101 index=-2
options snd-usb-us122l index=-2
options snd-usb-usx2y index=-2
# Ubuntu #62691, enable MPU for snd-cmipci
options snd-cmipci mpu_port=0x330 fm_port=0x388
# Keep snd-pcsp from being loaded as first soundcard
options snd-pcsp index=-2
# Keep snd-usb-audio from beeing loaded as first soundcard
options snd-usb-audio index=-2

and this is exactly the file where you can statically bind sound cards
. Since I wanted to set static values ​​​​for sound devices, if you look at them through aplay - l, then this is a number, after the word "card", I had to get into /proc/asound/, where I saw card1 and card2, if you look into these directories, you can see the usbid file, in which I saw values ​​like xxxx:xxxx, then I took this value and added it to /etc/modprobe.d/alsa-base.conf in the form where snd-usb-audio is the identifier of any usb audio card index is the serial number id - usbid, which was mentioned above After adding, I rebooted the machine, registered aplay - l
options snd-usb-audio index=2 id="xxxx:xxxx"
and got the desired result, no matter how much I reboot, no matter how much I rearrange the cards, they will always be at the number that I registered in the index

Answer 2

I have not tried this with USB sound cards, but udev helps us to hang USB modems on the correct devices. Here is a link to start with, there are some good examples.
https://www.tecmint.com/udev-for-device-detection-...

Answer 3

There was such question only with Arduino. Also used rules in udev. I followed this example and it works:

You could try creating a udev rule that will create a symlink to that USB device and then you can use something like /dev/myUSB which will always remain the same for that particular USB device.
First you need to find some identifying information for the USB drive. Typing lsusb should display some information that looks like this:
Bus 001 Device 004: ID 0403:6001 Future Technology Devices International
In this example, 0403 is the Vendor ID and 6001 is the Product ID.
Create a file called 99_usbdevice.rules (I don't think the name matters, just the directory):
sudo nano /etc/udev/rules.d/99_usbdevices.rules
Note that the directory above may be specific to Raspbian.
Copy/paste the line below to a file and save it:
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", SYMLINK+="myUSB"
Reboot Pi or unplug USB and try again paste it. There should now be a /dev/myUSB entry which you can use in the same way as the ttyUSB# entry.