From owner-freebsd-hackers  Wed Aug  2  1:22: 9 2000
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Date: Wed, 02 Aug 2000 01:22:05 -0700
From: Nick Sayer <nsayer@quack.kfu.com>
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To: freebsd-hackers@FreeBSD.ORG
Subject: ESS Solo driver almost there (was Re: US$100 prize for adding ESS 
 Audiodrive support to pcm)
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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?


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