[alsa-devel] PATCH - MIDI on ice1724 - real-time kernel problem SOLVED(?)

Pavel Hofman pavel.hofman at insite.cz
Fri Jun 27 15:54:41 CEST 2008

Martin Krüger wrote:
> Martin Krüger schrieb:
>> Hi Pavel,
>> sorry for the long break, i was really busy at studying.
>> ---snip---
>> Thanks a lot,
>> Martin
>> _______________________________________________
>> Alsa-devel mailing list
>> Alsa-devel at alsa-project.org
>> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> Hi again,
> i did some other playing around this evening. (Debugging would be a word 
> much too big...)
> I commented out the logic stuff in the following subroutines of the 
> ice1724.c:
> - static int vt1724_midi_output_open(struct snd_rawmidi_substream *s)
> - static int vt1724_midi_output_close(struct snd_rawmidi_substream *s)
> - static void vt1724_midi_output_trigger(struct snd_rawmidi_substream 
> *s, int up)
> - static void vt1724_midi_output_drain(struct snd_rawmidi_substream *s)
> The vt1724_enable_midi_irq(s, VT1724_IRQ_MPU_TX, 1) is killing my 
> kernel, i don't know why.

So enabling the MPU TX interrupt causes lockup. Very similar to my 
experience with the previous version of the MIDI driver. Please put a 
debug line to snd_vt1724_interrupt, listing status bits for each 
interrupt. That was the place I experienced loops etc. In my case the 
flood eventually fooled the logging facility, but I could still read the 
first few logs.

> On the input side everything works, so i am a bit confused. Again. ;-)

I was also getting only TX interrupt floods, RX was OK.

Good luck,


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