FreeLists / openbeos-midi / [openbeos-midi] Re: MPU401 Specifications - maybe

[Crain Greg <greg.crain@xxxxxxxxxxx>]

>So, yes, we don't really need the full documentation.
>However, there is this "workaround" argument in mpu401->create_device() api 
>which let me think that there is some tricks to support some MPU401 
>*mostly* compatible cards out there, and to much documentation never can't 
>hurt 
>here.
>-Philippe, proud midi team mailing-list lurker ;-)

I'm still having trouble with my driver getting the module to work (emu10k2).  
It gets into UART mode, but no midi data. I found this note at the Alsa driver 
site:
"Some soundchips have similar but a little bit different implementation of 
mpu401 stuff. For example, emu10k1 has its own mpu401 routines".
I really wonder what that "workaround" is.

I do have a question that is kinda related:
I was going to try bypassing the module write and just write directly to the 
UART.
Seems the midi server sends this data to the write hook: 

        status_t (*write_hook)(void * cookie, off_t pos, const void * data, 
size_t * len);

Is there a way to determine what the 'const void * data' is ?  I don't know 
what to cast it to.  len was 3, pos was 0.  The message was a simple C note, 
key on.  I figured a 3 byte message, with 'data' being a simple pointer buffer. 
  Any hints, or am I totally confused ?

Greg, struggling driver hacker  :-)