Subject: Re: Advice to people writing audio drivers
To: Charles M. Hannum <firstname.lastname@example.org>
From: Ignatios Souvatzis <email@example.com>
Date: 01/26/1999 11:11:12
On Mon, Jan 25, 1999 at 09:27:01PM -0500, Charles M. Hannum wrote:
> I *know* I've been over this before, but...
> > Will using trigger become mandatory?
> > [description of board]
> This is simply not an issue. If you have to upload the data in
> blocks, then you can always write a function that's called from both
> the trigger and interrupt routines (analogous to the old `start'
> routine). There's no reason for this division to be in the interface.
> (And in fact, uploading the next block from a callback, as was
> previously done, significantly increases the gap between blocks, which
> on some hardware caused a FIFO underrun and an audible glitch.)
> > What should 44100-only hardware do?
> If the hardware simply can't support the `standard' default settings,
> that's fine. But some of the drivers were just being lame.
> > MMAP even for non-DMA drivers?
> Yes. Even for hardware that doesn't do DMA, it's still faster to
> avoid the extra copying to get the data into the ring buffer.
> And it's quite trivial to support.
It would help if you would update audio(9).