Re: something went wrong with USB iJack data in kernel 6.x

[Takashi Iwai <tiwai@suse.de>]

On Mon, 14 Oct 2024 09:36:35 +0200,
Takashi Iwai wrote:
> 
> On Sun, 13 Oct 2024 18:56:57 +0200,
> Paul Davis wrote:
> > 
> > I don't know where to start with this issue, but since I noticed it
> > trying to use a MIDI device, I thought I would start here. Advice on
> > where to take it would  be much appreciated.
> > 
> > High Level symptoms:
> > 
> > 1. plugin in a Novation Lanchkey mk4 to (a) a system running kernel
> > 6.x (b) a system running kernel 5.x
> > 2. run aplaymidi -l or arecordmidi -l
> > 
> >   Results:
> >      (a) kernel 6.x: note the presence of two identical MIDI port
> > names for the device
> >      (b) kernel 5.x: note the presence of two differently named MIDI
> > ports for the device
> > 
> > Mid-level diagnosis:
> > 
> > Run lsusb -v on both kernels. For 5.x, note that the iJACK displays
> > include a string for the MIDI port name. For 6.x note that this string
> > is missing.
> > 
> > Working with devices bearing identical ports for multiple names ranges
> > from extremely difficult to impossible.
> > 
> > I have no idea what layer of the stack can be involved here, other
> > than that it is not hardware. I've run both 5.x and 6.x kernels on the
> > same system.
> 
> Could you try to narrow down the regression range, e.g. by testing
> different 5.x and 6.x kernels?  The best would be git-bisect, but
> figuring out the first broken kernel version would help a lot
> already.
> 
> Also the issue can be very specific to the device, so please give the
> details of your device.  e.g. the alsa-info.sh outputs from both cases
> as well as lsusb -v outputs. 

And, if it's about iJack handling for MIDI v1.x, the only recent
change I can see is the upstream commit
41c25e193b2befc22462aa41591d397fab174ca1
    ALSA: usb-audio: More relaxed check of MIDI jack names

You can try to revert it.


Takashi