[alsa-devel] MiniDSP USBStreamer / UAC2 / Alsamixer bogus

[Jan Baumgart]

Hi Daniel,

Thanks for the guidance!
I don't have the unit at hand right now, but will give it a try next 
week and see what I can find...

All the best,
Jan

On 5/23/14 7:18 PM, Daniel Mack wrote:
> Hi,
>
> On 05/22/2014 07:36 PM, Jan Baumgart wrote:
>>           AudioControl Interface Descriptor:
>>             bLength                16
>>             bDescriptorType        36
>>             bDescriptorSubtype      9 (EXTENSION_UNIT)
>>           Warning: Descriptor too short
>
> Hmm, lsusb is right here - bLength should be 16+p ...
>
>>             bUnitID                51
>>             wExtensionCode          0
>>             bNrPins                 1
>
> ... where p is this value: 1.
>
>>             baSourceID( 0)          2
>>             bNrChannels             8
>>             wChannelConfig          0
>>             iChannelNames           3
>>             bmControls        0x00
>>             iExtension             42
>
> Hence, the iExtension value is wrong, ...
>
>>           AudioControl Interface Descriptor:
>>             bLength                42
>
> because it actually is bLength of the next descriptor. So there's
> definitely a problem in the USB descriptors, I'm just not sure how we
> should deal with that.
>
> I'm also not entirely sure if that explains your control name trouble.
> If you're interested in debugging this, have a look at the function
> sound/usb/mixer.c, function build_audio_procunit(), especially the lower
> half where we try to determine a nice name for the new control. You
> could start dumping the variable 'nameid' and see what it contains.
>
> Also, this device reports strings to describe the channel names
> (iChannelNames), which the driver currently doesn't care about. It might
> be worth fetching them and see what they contain. On the other hand,
> ALSA doesn't allow us to provide names for individual sub-controls (for
> each of the 8 mixer values inside one control).
>
> Are you up for a little trial and error? I doubt that this will fix your
> clock selector trouble though, but for that, the usbmon traces should
> give a hint.
>
>
> Best regards,
> Daniel
>

-- 
Jan Baumgart
Technischer Mitarbeiter
Hochschule für Musik und Darstellende Kunst
Eschersheimer Landstr. 29-39
60322 Frankfurt am Main