[LAU] Assigning devices at boot up.

[Jeremy Jongepier]

Hello,

On 08-12-2020 16:44, Bill Purvis wrote:
> On 08/12/2020 15:30, Florian Paul Schmidt wrote:
>> Hi,
>>
>> if the USB device id is different for the two usb devices then you might
>> just write a custum udev-rule that loads the snd-usb-audio module with
>> different card index parameters..
>>
>> Regards,
>> FPS
> That's my problem, the keyboards are identical models and the only thing
> that
> will distinguish them is the slot they are plugged into. I haven't got
> as far
> as plugging both in and looking if there is a correlation between the
> information
> provided by lsusb and the Alsa slot id. I think I can get them on
> separate hubs
> which might be useful. I know very little about what goes on when
> devices are
> initialised. If all else fails, I'll have to plug one into an Arduino
> and use
> that to shift the channel number, but I had hoped to avoid going that far!
> 
> Bill
> 

If the keyboards are on different USB buses you can use that difference
to distinguish between them. Like Florian said you can use Udev for
this. Did a quick search and this might be useful:
https://github.com/dh1tw/remoteAudio/wiki/Persistent-USB-Mapping-of-Audio-devices-(Linux)#udev-rule-based-on-usb-port
lsusb can tell you which keyboard lives on which USB bus, bear in mind
that different USB ports can live on the same bus. So the trick is to
find out if there are USB ports living on different buses and connecting
the keyboards to those specific ports.

Best,

Jeremy

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