[FS#256] usb audio doesn't work - "no such device"

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Dmitry (f3flight) 

Attached to Project - LEDE Project
Summary - usb audio doesn't work - "no such device"
Task Type - Bug Report
Category - Kernel
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - - Xiami Mi Mini - https://wiki.openwrt.org/toh/xiaomi/mini
- Trunk version 2016-10-30 downloaded from https://downloads.lede-project.org/snapshots/targets/ramips/mt7620/lede-ramips-mt7620-miwifi-mini-squashfs-sysupgrade.bin
- Steps to reproduce:
1. install kmod-usb-audio, alsa-utils-tests
2. reboot
3. plug in a usb-audio device (in my case it is Behringer UMC404)
4. run "speaker-test", the output will be:

root at mi:~# speaker-test

speaker-test 1.1.0

Playback device is default
Stream parameters are 48000Hz, S16_LE, 1 channels
Using 16 octaves of pink noise
ALSA lib pcm_direct.c:1159:(snd1_pcm_direct_initialize_poll_fd) unable to open timer 'hw:CLASS=3,SCLASS=0,CARD=0,DEV=0,SUBDEV=0'
ALSA lib pcm_dmix.c:1106:(snd_pcm_dmix_open) unable to initialize poll_fd
Playback open error: -19,No such device


This is a regression since OpenWRT 15.05.1 release where it works, most likely related to newer kernel

 

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=256