[alsa-devel] Basic DMA question

[Takashi Iwai]

At Mon, 26 Mar 2007 11:28:59 +0200,
Sven Johnsson wrote:
> 
> Rene,
> 
> I have already read the ALSA driver document. What I really like to
> understand is when DMA transfers are invoked, and what the source and
> destination for the transfer is.

The DMA transfer is started/stopped in trigger callback.
In the case of typical playback, the source is the buffer the driver
allocated (in hw_params callback) and the destination is the
hardware.  The DMA setup is usually done in prepare callback.


Takashi

> 
> Regards,
> Sven
> 
> 2007/3/26, Rene Herman <rene.herman at gmail.com>:
> > On 03/26/2007 03:13 AM, Sven Johnsson wrote:
> >
> > > I'm new to writing ALSA drivers, and I could use some help on
> > > clarifying how DMA is used in ALSA.
> >
> > "Writing an ALSA Driver" is a useful document. Google will find it...
> >
> > By the way, the alsa-devel mailinglist recently moved from
> > sourceforge.net to alsa-project.org directly and the new list is
> > moderated for non-subscribers. I just approved your message from the
> > moderation queue manually, but please consider subscribing, at:
> >
> > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> >
> > Thanks,
> > Rene
> >
> >
> >
> >
> > >
> > > Regards,
> > > Sven
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> > >
> >
> >
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