[linux-audio-dev] mpu401 fifo scheduling on linux2.4.18

Frank van de Pol fvdpol at home.nl
Fri Nov 22 09:05:01 UTC 2002

The timer frequency I was refering to is the linux kernel scheduling
frequency, ie. the (asm/param.h) HZ constant. Since of 2.5 kernel it is
increased from 100 tot 1000 btw.

For you're first question I'm not aware of a conclusive list. It would be
good to have it though, since I was tricked with the same CMI PCI card flaw,
not even considering that these design errors are still being made (and
possibly even under the excuse of maintaining SB crap compatibility huh).

I'll try to give you a list of cards _I_ know the status of:

Bad MIDI transmission:
	Soundblaster 16
	Soundblaster AWE64
	C-Media CMI8738 

Good MIDI transmission:
	Gravis Ultrasound Max
	Ensoniq AudioPCI
	Soundblaster 128 (PCI)
	Soundblaster Live

Of course many more options exist, perhaps others know some more details.


On Fri, Nov 22, 2002 at 09:15:55PM +0000, Bruce M Beach wrote:
> On Fri, 22 Nov 2002, Frank van de Pol wrote:
> > Hi Bruce,
> > the cmpci cards have the same hardware design error as the older soundblaster
> > cards (eg. SB16/AWE64). The cards lack the ability to generate interrupts.....
> > If you want to drive your external MIDI gear, just use an interface which
> > has a decent MIDI port. In case you do not have the option to fix the ...
> > ....... a high (2 kHz) timer frequency instead of the standard 100 Hz.
> > Frank.
>    Hello Frank
>      Thanks for the reply. Just for fun, I downloaded the alsa code and tried
>      the midi fifo (midiC0D0), and got fairly chaotic results, which I suspect
>      was due to the 'timer' frequency, which I don't really understand what
>      it is. As far as the lack of an interupt goes for the card, upon reflection
>      I would imagine writeing a polling type driver for a multitasking system
>      as something of a hideous nightmare. Fortunately I am not stuck with
>      the cmipci card. I can replace it. I also have another option which I like
>      better. The korg has a jack for a standard serial port which I'll try to
>      hook up.
>    Bruce

+---- --- -- -  -   -    - 
| Frank van de Pol                  -o)    A-L-S-A
| FvdPol at home.nl                    /\\  Sounds good!
| http://www.alsa-project.org      _\_v
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