Hello,
I am attempting to use the USB audo gadget uac2 so that my i.MX6
based Wandboard can be a USB audio device.
I am using a stock 4.5 linux with no modifications, direct from git
and compiled locally:
uname -a shows:
Linux wandboard 4.5.0 #4 SMP Tue Jun 7 10:09:16 PDT 2016 armv7l armv7l
armv7l GNU/Linux
I have brought up and configfs setup, and have successfully gotten
aplay and arecord to show the devices like this:
aplay -L shows:
...
hw:CARD=UAC2Gadget,DEV=0
UAC2_Gadget, UAC2 PCM
Direct hardware device without any conversions
...
and arecord -L shows:
...
hw:CARD=UAC2Gadget,DEV=0
UAC2_Gadget, UAC2 PCM
...
I have tried both 48000 and 64000 sample rates (via s_srate and
c_srate), but I can't either play or record audio, and nothing goes
over to the host.
On the host side, I can play and record -- i.e. time progresses
without error in audacity when I hit the record button (which does a
full-duplex play/record).
On the client side I get this, regardless of what's happening on the host side:
...
root@wandboard:/home/caleb/gadget# aplay -D hw:CARD=UAC2Gadget,DEV=0 sine64k.wav
Playing WAVE 'sine64k.wav' : Signed 16 bit Little Endian, Rate 64000 Hz, Stereo
aplay: pcm_write:1939: write error: Input/output error
...
Here is the script I use for starting the gadget interface:
cd /sys/kernel/config/usb_gadget
mkdir g1
cd g1
echo "0x1d6b" > idVendor
echo "0x0104" > idProduct
mkdir strings/0x409
echo "0123456789" > strings/0x409/serialnumber
echo "Foo Inc." > strings/0x409/manufacturer
echo "Bar Gadget" > strings/0x409/product
mkdir functions/uac2.aud0
mkdir functions/ecm.usb0
#echo 64000 > functions/uac2.aud0/c_srate
#echo 64000 > functions/uac2.aud0/p_srate
mkdir configs/c.1
mkdir configs/c.1/strings/0x409
echo "CDC ECM + audio" > configs/c.1/strings/0x409/configuration
ln -s functions/uac2.aud0 configs/c.1
ln -s functions/ecm.usb0 configs/c.1
echo `ls /sys/class/udc/` > /sys/kernel/config/usb_gadget/g1/UDC
When I run the script above I get the following dumped into /var/log/syslog:
Jun 8 23:08:14 wandboard kernel: [ 139.994081] using random self
ethernet address
Jun 8 23:08:14 wandboard kernel: [ 139.994107] using random host
ethernet address
Jun 8 23:08:14 wandboard NetworkManager[359]:
nm_device_get_device_type: assertion 'NM_IS_DEVICE (self)' failed
Jun 8 23:08:14 wandboard NetworkManager[359]: <info> (usb0): new
Generic device (carrier: OFF, driver: 'g_ether', ifindex: 4)
Jun 8 23:08:14 wandboard kernel: [ 140.125255] usb0: HOST MAC
3e:52:2d:0d:98:fe
Jun 8 23:08:14 wandboard kernel: [ 140.153803] usb0: MAC 0e:cf:aa:06:aa:8a
Jun 8 23:08:14 wandboard systemd-udevd[773]: Failed to apply ACL on
/dev/snd/controlC3: Operation not supported
Jun 8 23:08:14 wandboard systemd-udevd[776]: Failed to apply ACL on
/dev/snd/pcmC3D0c: Operation not supported
Jun 8 23:08:14 wandboard systemd-udevd[775]: Failed to apply ACL on
/dev/snd/pcmC3D0p: Operation not supported
Jun 8 23:08:14 wandboard systemd-udevd[773]: Process
'/usr/sbin/alsactl -E HOME=/var/run/alsa restore 3' failed with exit
code 99.
Jun 8 23:08:14 wandboard NetworkManager[359]: <info> devices added
(path: /sys/devices/soc0/soc/2100000.aips-bus/2184000.usb/ci_hdrc.0/gadget/net/usb0,
iface: usb0)
Jun 8 23:08:14 wandboard NetworkManager[359]: <info> device added
(path: /sys/devices/soc0/soc/2100000.aips-bus/2184000.usb/ci_hdrc.0/gadget/net/usb0,
iface: usb0): no ifupdown configuration found.
Any idea what could be wrong?Is the 'Failed to apply ACL' relavent?
Thank you!
Sincerely,
-Caleb
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