[alsa-devel] Tascam US-122L - Corrupt USB descriptor

[Simon Wood]

On Wed, April 13, 2016 3:01 am, Clemens Ladisch wrote:
> Simon Wood wrote:
>
>> I have been struggling for the past few days to get a Tascam US-122L
>> (USB
>> sound-card/midi interface) working, despite reading numerous forum
>> postings I have only been able to get the midi portion working.
>
> Does it show up with "aplay -l"?

The card shows up under '/proc/asound/cards', but only as Midi. See
attached for full listing.


>> I note that the USB descriptor seems to be corrupt. It declares 2
>> interfaces, but then describes 3 separate with the same interface number
>>  for the last 2.
>
> The descriptors describe two alternate settings for the same interface.
> This is a feature, which is required for audio devices.
>
>
>> iManufacturer           1 (error)				<------ Here be Errors! iProduct
>> 2 (error)
>> iSerial                 3 (error)
>
> It's possible that lsusb does not have the permissions needed to send
> the messages to ask for the strings.  Try running it as root.

Was running as root (on Xubuntu, 2 different machines, different installs).

I note that sometimes this is OK, ie when I do '# echo 0 >
/sys/bus/usb/devices/1-2/bConfigurationValue', but then I have no
interfaces at all (no midi, no listing).

Can anyone confirm they have a US-122L working on a new kernel. Is the USB
descriptor the same as what I'm seeing, perhaps hardware changed at some
point.
Cheers,
Simon
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