Re: Question about rawmidi input trigger

[Lee Revell <rlrevell@joe-job.com>]

On Wed, 2006-06-28 at 20:16 +0200, Takashi Iwai wrote:
> At Wed, 28 Jun 2006 14:06:59 -0400,
> Lee Revell wrote:
> > 
> > I'm writing a MIDI driver for hardware that is not available yet, so for
> > now I'm just doing simulation.  To simulate MIDI input I just use a
> > timer that calls snd_rawmidi_receive(substream_input, &dummy_data, 1).
> > 
> > Is it normal for the MIDI input trigger callback to be called over and
> > over in a loop when I run "arecordmidi"?  Or should it only be called
> > once, when the stream is opened?
> 
> It's normal.  The driver should remember that the device was already
> triggered and just ignore the succeeding trigger call or do some
> useful thing (for example, mpu401_uart peeks the input FIFO for
> hardwares that don't support proper input irq). 

OK, great.

I ask because I am working off of emumpu401.c as an example, which does:

static void
snd_emu10k1_midi_input_trigger(struct snd_rawmidi_substream *substream,
int up) 
{
[...]
        if (up)
                snd_emu10k1_intr_enable(emu, midi->rx_enable);
        else
                snd_emu10k1_intr_disable(emu, midi->rx_enable);
}

And it seemed kind of wrong that the EMU driver would enable RX
interrupts over and over while recording.

I guess it just means the EMU driver is not as efficient as it could
be?  ;-)

Lee


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