[alsa-devel] MIDI issue with RME HDSPM MADI

[Jörn Nettingsmeier]

On 06/05/2011 02:34 PM, Jörn Nettingsmeier wrote:
> On 06/03/2011 06:08 PM, Takashi Iwai wrote:
>> At Wed, 01 Jun 2011 19:27:32 +0200,
>> Jörn Nettingsmeier wrote:
>>>
>>> Hi *!
>>>
>>>
>>> The HDSPM MADI driver seems to have an issue with its MIDI
>>> implementation. It is rock-solid for audio under Jack at 64
>>> frames/period, but as soon as I start using the MIDI over MADI interface
>>> (to remote-control my Micstasy preamps), I'm getting xruns every ten
>>> seconds or so.
>>
>> Maybe we can just replace the midi stuff into workqueue.
>> Below is a very quick and untested patch.  Does it work?
>
> patch applies and works, no crashes here.
> but no change in xrun behaviour either.
>
> for the record, i'm running the kernel with threadirqs.
>
> i guess by using a workqueue, we have eliminated the possibility that
> anything in the midi bottom half of the driver is hogging the hardware
> resources to cause an xrun, right?

new datapoint: the xruns are the same when i use the physical midi 
interface of the HDSP MADI instead of the MIDI over MADI one.

i wonder: can anybody reproduce this issue with another card supported 
by the hsdpm.c driver?
if it's higher up in the code, it should affect other hardware as well. 
or maybe not, since the problem might not show on cards with less than 
64 channels...

i'm digging through some kernel-related books regarding scheduler 
instrumentation, but progress is kinda slow... if anyone could suggest 
some hot leads to follow, i'd be glad to :)

best,


jörn



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