[alsa-devel] Steinberg MIDEX8 driver attempt

[Clemens Ladisch]

Hedde Bosman wrote:
> I've owned a MIDEX8 for some years now and am now attempting a driver
> for it. [...]
> it looks a bit like the standard usb midi class, but it requires some
> periodic (i guess timer) messages on endpoint 0x02

Why "requires"?  What happens if you do not send them?

> Not all (interrupt) urbs that are submitted will complete (within 25
> ms at least).

And why would that be a problem?

> Sometimes after sending a few messages, an empty urb shows up in
> wireshark. However, in code, there's an if-statement that should allow
> only messages of length > 0 to be submitted (line 568, if (num_read >
> 0)).

Try adding a check before the actual usb_submit_urb() call, but nothing
would protect against your code accidentally changing the
transfer_buffer_length of an active URB field later.

> Might this have to do with issue 1?

Not unless you have mixed up input and output URBs.


Regards,
Clemens