From owner-freebsd-hackers  Wed Aug  2  1:24:24 2000
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Date: Wed, 2 Aug 2000 00:31:08 -0700
From: Alfred Perlstein <bright@wintelcom.net>
To: Nick Sayer <nsayer@quack.kfu.com>
Cc: freebsd-hackers@FreeBSD.ORG
Subject: Re: ESS Solo driver almost there (was Re: US$100 prize for adding ESS Audiodrive support to pcm)
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* Nick Sayer <nsayer@quack.kfu.com> [000802 00:30] wrote:
> Channel 2 works now, and channel 1 is almost working. I ran across this
> note in the
> NetBSD source for their Solo driver...
> 
> 
>         /*
>          * Apparently the Audio 1 DMA controller's current address
>          * register can't roll over a 64K address boundary, so we have
> to
>          * take care of that ourselves.  The second channel DMA
> controller
>          * doesn't have that restriction, however.
>          */
> 
> It would make sense that the results I'm seeing with the current driver
> might be
> caused by this bug (it sounds like a square wave is slecting between the
> audio
> playback and a white noise source when playing back 16 bit audio. The
> frequency
> of the square wave is proportional to the data rate at the time).
> 
> Does anyone know how one might place a restriction on a PCM driver's DMA
> buffer
> that it not cross a (physical) 64k boundary?

Do you mean allocating it with contigmalloc?

-Alfred


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