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To: Stephen McKay <syssgm@dtir.qld.gov.au>
cc: freebsd-current@FreeBSD.ORG
Subject: Re: isa.c:isa_dmastatus(int chan) 
In-reply-to: Your message of "Fri, 15 Aug 1997 20:20:34 +1000."
             <199708151020.UAA02923@ogre.dtir.qld.gov.au> 
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Date: Fri, 15 Aug 1997 09:37:18 -0700
From: Amancio Hasty <hasty@rah.star-gate.com>
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For now , I am just going to duplicate isa_dmastatus in the  sound driver.

I can call isa_dma_acquire  however that leaves me wide open for 
the second condition .

	Tnks,
	Amancio

>From The Desk Of Stephen McKay :
> On Friday, 15th August 1997, Amancio Hasty wrote:
> 
> >Can someone delete the enclosed data from isa_dmastatus?
> >
> >
> >isa_dmastatus(int chan)
> >{
> >	u_long	cnt = 0;
> >	int	ffport, waport;
> >	u_long	low1, high1, low2, high2;
> >	u_long	ef;
> >/* delete this block of code */
> >	/* channel active? */
> >	if ((dma_inuse & (1 << chan)) == 0) {
> >		printf("isa_dmastatus: channel %d not active\n", chan);
> >				return(-1);
> >	}
> >
> >	/* still busy? */
> >	if ((dma_busy & (1 << chan)) == 0) {
> >	    		return(0); 
> >	}
> >	
> >/* end of delete block */
> 
> Calling isa_dma_acquire() first will satisfy the first condition, and I
> think it makes sense to do so.  The second condition is trickier, and
> whether or not it should be deleted depends on what you mean by "busy".
> Once the channel is in cascade mode, you can think of it as busy.  So,
> in that case, you would add "dma_busy |= 1 << chan" to isa_dmacascade().
> You might have other opinions of cascade mode, then the fix is different.
> 
> >isa_dmastatus is really meant for the sound driver and we are using
> >in auto dma mode.
> 
> But it should work for everything.  Although this routine has been debated
> already, it still needs some improvement.
> 
> Stephen.