Date: Thu, 24 Jul 1997 18:59:07 -0400 From: Brian Campbell <brianc@pobox.com> To: freebsd-multimedia@FreeBSD.org Subject: Re: sb16 request Message-ID: <19970724185907.39493@pobox.com> In-Reply-To: <199707241343.PAA26156@labinfo.iet.unipi.it>; from Luigi Rizzo on Thu, Jul 24, 1997 at 03:43:15PM %2B0200 References: <19970724071551.54552@ct.picker.com> <199707241343.PAA26156@labinfo.iet.unipi.it>
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On Thu, Jul 24, 1997 at 03:43:15PM +0200, Luigi Rizzo wrote: > I am looking at the sb16 operation in full duplex using dual dma (one > 8-bit, the other 16-bit): > > Which one fo the following approaches people prefers: > > 1. always use 16-bit for play, 8-bit for record; > 2. always use 16-bit for record, 8-bit for play; > 3. allocate the 16-bit channel to the first type of request (read or > write) and use the 8-bit channel for the other one. > > or > > 4. define a new ioctl to chose which channel gets the 16-bit dma and > which one gets the 8-bit dma, with some default camong those > described before. There's already a mechanism to specify the number of bits used for playback/record and its format. The default on open() is 8-bit (I think) and I suppose it should remain that way. If either playback or record wants 16-bit then the appropriate ioctl should be used. If the other channel requested it first, the second will fail. I'm assuming two descriptors are in use, one RDONLY the other WRONLY.
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