[alsa-devel] How to add a new MIDI device to the usbaudio driver

Daniel Mack zonque at gmail.com
Tue Aug 23 11:22:52 CEST 2011

On Tue, Aug 23, 2011 at 11:03 AM, Paul Menzel
<paulepanter at users.sourceforge.net> wrote:
> Am Dienstag, den 23.08.2011, 10:43 +0200 schrieb Daniel Mack:
>> On Tue, Aug 23, 2011 at 9:35 AM, Kristian Amlie <kristian at amlie.name> wrote:
>> > On 08/22/11 13:49, Daniel Mack wrote:
>> >> It doesn't seem to be using a standard MIDI interface, but there's a
>> >> chance that it accepts raw MIDI byte streams. Can you check the patch
>> >> below?
>> >
>> > With that patch, the device shows up, but aseqdump does not report any
>> > MIDI events after connecting to it.
>> >
>> > The Windows drivers are called "USB Serial Converter" and "USB Serial
>> > Port", so maybe it's all wrapped in a different protocol. Does that name
>> > ring a bell?
>> That's possible, and it should be easy to support these type of
>> devices in ALSA. However, some logic is neccessary to configure the
>> hardware to its correct baud rate and hardware protocol. The easiest
>> way to determine the setup sequence is certainly to sniff the Windows
>> driver communication with some tool like usbsnoop. Can you give that a
>> try?
> … and ask the manufacturer about GNU/Linux support.
> Something like, you bought the hardware and expect it to work
> everywhere. Additionally they make money by selling the hardware and not
> developing a driver, so they should publish the documentation and even
> pay someone – like Daniel or Clemens ? – to write the support for their
> hardware. (Only when they say they do not have any money or something
> like that, you can also tell them to donate/provide free hardware for
> the developer and a contact address to their M$ Windows developer for
> questions.)

While I agree in general to your points, I think its not worth the
effort in this particular case. It's probably very easy to add support
for this by just sending one magic usb_control_msg up-front, and it's
not complicated to sniff that value. From a customer standpoint,
again, I'm sure the manufacturer will just state that they didn't
promise any Linux support, and so you can't claim it.


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