[yocto] Why isn't USB MIDI working?

[Iorga, Cristian]

Hi Paul,

Please file in a bug report as an enhancement regarding USB MIDI support.
We will see what we can do for 1.5.

Regards,
Cristian

-----Original Message-----
From: yocto-bounces at yoctoproject.org [mailto:yocto-bounces at yoctoproject.org] On Behalf Of Paul D. DeRocco
Sent: Wednesday, April 17, 2013 3:51 AM
To: 'Paul Eggleton'
Cc: yocto at yoctoproject.org
Subject: Re: [yocto] Why isn't USB MIDI working?

> From: Paul Eggleton
> 
> On Sunday 14 April 2013 15:49:12 Paul D. DeRocco wrote:
> > I've built core-image-base-cedartrail-nopvr, which includes ALSA. 
> > /dev/snd properly contains the devices for my mobo, and 
> > /proc/asound/devices lists them as well. If I plug in a USB MIDI 
> > device (a USB to MIDI converter), I see the USB connect message on 
> > the console, but no device is added to /dev/snd or 
> > /proc/asound/devices. Anyone have any idea why?
> > I've tried an
> > eMu XMidi1x1, and a cheap generic converter. Both work fine under 
> > Ubuntu, on the same mobo.
> 
> Typically two things are required for a USB device to work - a driver, 
> and an appropriate udev rule to associate the driver with the device. 
> Do you have USB midi support enabled in the kernel? If so, is there a 
> udev rule for USB midi devices? If there isn't, presumably you could 
> just use Ubuntu as a reference for that.

I apologize for my ignorance, but I really don't know how to go about figuring this out.

There is a file called /lib/udev/rules.d/60-persistent-alsa.rules, which is full of cryptic stuff that I don't understand, including two lines referring to usb, but nothing specifically about MIDI. I compared it to the file on Ubuntu, and it's similar but not the same, but I have no idea whether any of the differences are meaningful. They're both small, so I've attached them.

Also, I see that while the alsa-utils recipe is being built, the resulting image only seems to have a couple of alsa utilities: alsamixer and alsactl, even though there are a whole lot more listed in meta/recipes-multimedia/alsa/alsa-utils_1.0.25.bb.

And when I run the system, there is no /dev/snd/seq device, which is the main interface to all MIDI devices. I don't plan on using that, preferring to use the /dev/snd/midi* OSS emulation device which is supposed to appear when an individual device is connected, but that's not happening, either.

How do I find out if USB MIDI support is enabled in the kernel?

This is plain vanilla core-image-base-cedartrail-nopvr, without any modifications. ALSA is part of it. Isn't it supposed to just work?

-- 

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco at ix.netcom.com