Re: snd-aoa status update / automatic driver loading

[Johannes Berg <johannes@sipsolutions.net>]

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On Wed, 2006-05-24 at 08:15 +1000, Benjamin Herrenschmidt wrote:
> > Right, that's how snd-powermac does it. It has the nasty side-effect of
> > polluting the cache a lot though, since dbdma commands are 16 bytes
> > long. Am I wrong?
> 
> You don't have that much DBDMA commands that it would pollute the cache
> _a lot_ :) 

Ah, yeah, I guess so. Well I do have 32 dbdma commands, them being
spaced up in 16-bytes means 16 cachelines, no? I'm not sure how the
cache is wired up ...

> > Alsa calls this thing the 'pointer' :) The frame counter we currently
> > use is the frame counter register of the i2s bus controller, and I don't
> > see why we shouldn't do that instead of reading back all the dbdma
> > command status fields.
> 
> If you manage to have it properly in sync, that may work too.

Seems to work fine so far, even if bcm43xx kills a few interrupts ;)

johannes

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