Re: ALSA USB MIDI port names are poorly constructed and truncate iJACK names

[Takashi Iwai <tiwai@suse.de>]

On Tue, 22 Apr 2025 16:31:50 +0200,
Paul Davis wrote:
> 
> ALSA's USB MIDI support appears to construct MIDI port names by
> concatenating the iProduct name and the iJACK name. The problem with
> this is that there is a fixed length to the port name in ALSA, and for
> an increasing number of devices, this behavior truncates critical
> information from the end of the iJACK name.
> 
> For example, culled from lsusb output:
> 
> Bus 005 Device 098: ID 1235:0145 Focusrite-Novation Launchkey MK4 49
>   iProduct                2 Launchkey MK4 49
>     iConfiguration          4 Launchkey MK4 49
>       iInterface              5 Launchkey MK4 49 MIDI
>       iInterface              6 Launchkey MK4 49 MIDI Int
>         iJack                   7 Launchkey MK4 49 MIDI In
>         iJack                   8 Launchkey MK4 49 MIDI Out
>         iJack                   9 Launchkey MK4 49 DAW In
> 
> gives these port names:
> 
> 44:0    Launchkey MK4 49                 Launchkey MK4 49 Launchkey MK4
>  44:1    Launchkey MK4 49                 Launchkey MK4 49 Launchkey MK4
> 
> which is useless since it fails to include the "DAW" and "MIDI Out"
> parts of the iJACK names.
> 
> The correct fix, I think is to only prepend the iProduct name if that
> name is not present at the start of the iJACK name. This will cover
> devices where the manufacturer does *not* include the device name in
> the iJACK name, but will fix this situation for devices where they do
> (Novation and Arturia and many others do this).
> 
> If agreed, I can construct a patch for this.

So you're suggesting to remove the substring matched with iProduct at
copying from iJack name?  That'll make sense and go ahead.


thanks,

Takashi