Re: HDSP 9652 MIDI - A timing disaster?

[Takashi Iwai <tiwai@suse.de>]

At Mon, 13 Jan 2003 15:28:58 +0100 (MET),
Clemens Ladisch wrote:
> 
> Paul Davis wrote:
> > >The hdsp driver doesn't send more than one MIDI byte per timer tick.
> > >IMHO it should be modified to send in a loop until the FIFO is full
> >
> > that's what this tried to do:
> > (...)
> > how does this end up writing only a single byte? unless n_pending is
> > always either 0 or 1, which on closer inspection, i see that it is
> > ... yikes.
> >
> > >sending in output_trigger() instead of delaying it to the next timer tick.
> >
> > hmm. i modelled this code on another PCI driver that had MIDI
> > support. is there an example you can point me to that starts from
> > within the equivalent output_trigger?
> 
> e.g. isa/sb/sb8_midi.c or drivers/mpu401/mpu401_uart.c
> 
> And both output one byte at a time in a loop until the output fails.
> (However, snd_sb8dsp_midi_output_write() doesn't check for a full FIFO.)

well, generally it's not a good style to process in such a loop in the
primary interrupt handler.  we should rewrite them using tasklet...


Takashi


-------------------------------------------------------
This SF.NET email is sponsored by: FREE  SSL Guide from Thawte
are you planning your Web Server Security? Click here to get a FREE
Thawte SSL guide and find the answers to all your  SSL security issues.
http://ads.sourceforge.net/cgi-bin/redirect.pl?thaw0026en