[alsa-devel] No sound from usb on Motorola C350 cellphone

[Giovanni Maruzzelli]

Hi list participants,

I am using cellphones connected to soundcards as cheap gsm gateways
(more complex than that, actually. You can see the whole GPL project
at www.celliax.org).

Maybe there is a way to not using soundcards, that would be *so* much
better: I found that Motorola c350 phones after receiving an AT+MODE=8
command via USB, make available an usb sound device.

That would be wonderful (less cables, more robustness, etc). Problem
is: the usb sound device do not plays or captures samples.

I suspect that the usb audio has to be activated, maybe by an AT or a
P2K command.

Or that a quirk has to be added to the alsa driver (snd_usb_audio).

Do you know anything about (maybe the quirk to be added to ALSA driver...)?

Do you have any hint?

I'm available to do all the research-testing-debugging that may be useful.

What happens is as follow:
1) attach the c350 to usb
2) is recognized as acm0
3) send at+mode=8 to c350 (via minicom, for eg)
4) it changes its usbid, disconnect from usb, reconnect, is recognized
as acm1, makes available a sound device
5) at commands work on the new acm1
6) trying to use the audio device directly (eg aplay -Dhw:1) do not
give errors on play (but no sound is head on the phone), gives error
pcm_read 1349 on record (eg arecord -Dhw:1)
7) trying to use the audiodevice through alsalib does not gives errors
at all (eg -Dplughw:1) but does not caputeres samples, and no sound is
heard on the phone


In the tgz archive attached you can find the following files:

lusb_without -> result of lusb -vv with no device attached

lsusb_with_ACM0 -> result of lusb -vv with c350 just attached,
recognized as acm modem

lsusb_with_ACM1 -> result of lusb -vv with c350 after sending
at+mode=8 to him, he has disconnected and was recognized again, this
time as ACM1, with a lot of additional usb interfaces

dmesg-acm0 -> result of dmesg after first c350 attachment

dmesg-acm1 -> result of dmesg after at+mode=8 was sent to the c350

aplay-l -> result of aplay -l showing the c350 as an alsa device

stream0_pstop_cstop -> result of cat /proc/asound/C350/stream0 while not active

stream0_pstop_crun -> result of cat /proc/asound/C350/stream0 while
arecord -vv -Dplughw:1 -fS16_LE ciapa.raw (if using -Dhw:1 it fails
with error: "pcm_read:1349: read error: Input/output error"). arecord
does not gives errors, but do not write samples

stream0_prun_crun -> result of cat /proc/asound/C350/stream0 while
aplay and arecord -vv -Dplughw:1 -fS16_LE ciapa.raw (if using -Dhw:1
arecord fails with error: "pcm_read:1349: read error: Input/output
error", aplay works but no audio) arecord does not gives errors, but
do not write samples

aplay_play -> results of aplay

arecord_rec -> results of arecord

Thank you all in advance,

Giovanni Maruzzelli
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