Re: [Jack-Devel] Call for testing of MIDI Drivers in JACK 2

Devin Anderson wrote:
> When I first did research for writing this driver, I was looking
> through the ALSA kernel code, and noticed that the default behavior
> for the 'drain' method (when a driver doesn't set its own rawmidi
> 'drain' method) is to sleep for 50 milliseconds, and then return,
> regardless of whether blocking I/O is used or not.  So, one of the
> things I did with the 'alsarawmidi' driver is to call:
> 
>     snd_rawmidi_params_set_avail_min(rawmidi, params, 1);

This already is the default value.

> ... to make the driver wake up when any bytes are written to a port,
> and to avoid calling `snd_rawmidi_drain` completely.

The avail_min parameter controls only wakeups of the application.

The drain method is used only with output devices to wait for all data
in ALSA's buffer to be written to the device.  The only situation where
you would want to call it is when closing the device, where ALSA already
calls it automatically.


Regards,
Clemens

1302155818.3215_0.ltw:2,a <4D9D525D.5030000 at ladisch dot de>