[alsa-devel] Alsa: USB Class 2 Audio soundcard device disappears suddenly

[Joao Bonina]

----- Original Message -----
> From: Joao Bonina <bonina_2001 at yahoo.com>
> To: Alan Stern <stern at rowland.harvard.edu>
> Cc: "alsa-devel at alsa-project.org" <alsa-devel at alsa-project.org>; linux-usb <linux-usb at vger.kernel.org>; Daniel Mack <zonque at gmail.com>
> Sent: Wednesday, 1 August 2012, 11:07
> Subject: Re: [alsa-devel] Alsa: USB Class 2 Audio soundcard device disappears suddenly
> 
> 
> 
>> ________________________________
>>  From: Alan Stern <stern at rowland.harvard.edu>
>> To: Joao Bonina <bonina_2001 at yahoo.com> 
>> Cc: Daniel Mack <zonque at gmail.com>; 
> "alsa-devel at alsa-project.org" <alsa-devel at alsa-project.org>; 
> linux-usb <linux-usb at vger.kernel.org> 
>> Sent: Tuesday, 31 July 2012, 15:35
>> Subject: Re: [alsa-devel] Alsa: USB Class 2 Audio soundcard device 
> disappears suddenly
>> 
>> On Tue, 31 Jul 2012, Joao Bonina wrote:
>> 
>>>  You're right about the EMI message, it's happening when the 
> streaming stops.
>>> 
>>>  I've tried different cables before, but that didn't solve the 
> problem.
>>> 
>>>  The motherboard is an Alix 1D, and I'm using the onboard USB 2.0 
> ports.
>>> 
>>>  If this really is an EMI issue, guess I'll have to source some kind 
> of miniPCI-USB 2.0 card and see if that solves the problem.
>> 
>> Another possibility is to put a USB hub before the sound device.  That 
>> _might_ clean up the signal.
>> 
>> Alan Stern
>> 
> 
> 
> Thanks for that suggestion, Alan.
> 
> I  used a cheap hub that I had stashed away. At the begining that seemed to 
> solve the problem. But after a while, some clicks and pops became audible.
> 
> Disconnected it all for a while, and when I reconnected, the problem was back 
> again with this message on mpd.log:
> 
> Aug 01 05:57 : output: "USB" [alsa] failed to play: No such device
> Aug 01 05:57 : output: closed plugin=alsa name="USB"
> 
> 
> 
> This time, there's no EMI message in dmesg. 
> 
> 
> Still have to try copying files from one usb flash to another.
> 
> João Bonina
> 
> 

Did the copying test and all went well there.

Also did a usbmon 
session with the DAC disconnecting/reconnecting automatically. There was
 no EMI message in dmesg there, and I'm connecting the DAC through a USB
 hub.

Analyzed the usbmon log with Virtual USB analyzer, but 
couldn't find reasons there for the disconnection. I'm not very 
experienced in this subject, so excuse me if I'm missing something 
obvious here.

I have the usbmon log. If someone wants to take a look at it, please let me know and I'll send it.


Cheers,
Joao Bonina