203 lines
8.2 KiB
Groff
203 lines
8.2 KiB
Groff
.\"
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.\" Copyright (c) 1998, Luigi Rizzo
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 3, 1998
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.Dt PCM 4 i386
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.Os FreeBSD
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.Sh NAME
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.Nm pcm
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.Nd FreeBSD audio device driver
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.Sh SYNOPSIS
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.Cd "device pcm0 at isa? port? irq 5 drq 1 flags 0x15"
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.Sh DESCRIPTION
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The
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.Nm pcm
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driver provides support for various ISA sound cards that are compatible
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with the WSS/MSS specs, or with the SBPro and SB16. Only audio
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capture/playback is supported by the driver, and true full duplex
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operation is available on most cards.
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.Pp
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Apart from the usual parameters, the flags field is used to specify
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the secondary DMA channel (generally used for capture in full duplex
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cards). Flags are set to 0 for cards not using a secondary DMA
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channel, or to 0x10 + C to specify channel C.
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.Pp
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PnP audio cards are also supported using the
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.Nm pnp
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support which is available in FreeBSD starting from release 2.2.6.
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See the
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.Xr pnp 4
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manpage for more information. In particular, remember that unit
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numbers for (recognized)
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PnP cards are assigned after the legacy ISA devices, and that the
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actual resources (port, irq and drq) used by the driver are read from
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the PnP configuration and not from the "device pcm0" line.
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So, if you have the following line in your kernel config file:
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.Pp
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.Cd "device pcm0 ..."
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.Pp
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your first PnP audio card will be unit #1, i.e. it will be accessible
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as /dev/audio1, /dev/dsp1, etc.
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Many applications default to using /dev/audio, but appropriate
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symlinks will be created as a side-effect of the the following command:
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.Pp
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.Cd cd /dev
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.Cd ./MAKEDEV snd1
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.Pp
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The driver works best with WSS/MSS cards, which have a very clean
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architecture and an orthogonal set of features. They also happen to be
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among the cheapest audio cards on the market.
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Other cards such as SB and ESS have a more complex internal
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architecture, and often no documentation available. As a consequence,
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support for these cards is slightly worse.
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.Pp
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The driver does its best to recognize the installed harware and drive
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it correctly, so that you don't have to give too many details in the
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kernel config files. For PnP cards this is actually easy since they
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identify themselves. For legacy ISA cards, the driver first looks for
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MSS cards at addresses 0x530 and 0x604, then for SB
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cards at 0x220 and 0x240 (obviously, unless overridden in the kernel
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config file by specifying an address).
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.Sh IOCTL
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The driver supports most of the Voxware ioctls(), and most
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applications work unmodified (including popular mpeg players and linux
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binaries). A few
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differences exist (the most important one is the ability to use
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memory-mapped access to the audio buffers). As a consequence, some
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applications may need to be recompiled with a slightly modified
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audio module. See /usr/include/machine/soundcard.h for a complete
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list of the supported ioctls.
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.Sh SUPPORTED CARDS
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.Pp
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Below we include a list of supported codecs/cards, including, if
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possible, the pnp configuration information where applicable
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(we give default parameters, your actual resources may vary).
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.Bl -tag -width 2m % begin list
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.It CS4237, CS4236, CS4232, CS4231
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.Cd "pnp 1 0 os enable port0 0x534 port2 0x220 irq0 5 drq0 1 drq1 3"
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.Pp
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All these cards work perfectly in full duplex using the MSS mode.
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This chipset is used, among others, on the A/Open AW35 and AW32, on
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some Intel motherboards, and (the CS4231) on some non-PnP cards.
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.Pp
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The CS4232 is reported as buggy in the Voxware documentation but
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I am not sure if this is true. On one of my Intel motherboards,
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capture does not work simply because the capture DMA channel is
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not wired to the ISA DMA controller.
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.It GUSPnP
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.Cd "pnp 1 0 os enable port0 0x220 port1 0x320 port2 0x32c irq0 5 drq0 7 drq1 5"
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.Pp
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Supported in full duplex using the MSS mode. The GUSPnP does not use a
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real CS4231, and I suspect a bug in the emulation when operating
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with mu-law format. Since the card is discontinued, I did not bother
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to include special code to set the card in "Mode3" (where mu-law is
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known to work) and rather I use U8 format internally, and do the
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conversion in software within the driver. This loses resolution,
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so you should use 16-bit modes with this card when possible.
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.It Yamaha OPL-SAx
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.Cd "pnp 1 0 os enable port0 0x220 port1 0x530 port2 0x388 port3 0x370 irq0 5 drq0 1 drq1 3"
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.Pp
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Works perfectly in all modes. This chip is used in several PnP cards,
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but also (in non-PnP mode) on motherboards and laptops (e.g. the
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Toshiba Libretto).
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.It OPTi931
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.Cd "pnp 1 1 os enable port0 0x534 port2 0x220 port3 0xe0d irq0 10 drq0 1 drq1 6"
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.Pp
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The chip is buggy, but the driver has many workarounds to make it work
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in full duplex because for some time these were the only full duplex
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cards I could find. u-law formats uses U8 format internally because of
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a bug in the chip.
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.It SB16, Vibra16C, and old SB16/AWExx cards
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.Cd "pnp 1 0 os enable port0 0x220 irq0 5 drq0 1 drq1 5"
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.Pp
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These codecs have limited full duplex capabilities, by doing 8-bit
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in one direction and 16-bit in the other one. The driver supports this
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mode of operation but keep in mind that it is not a supported mode of
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operation from CreativeLabs.
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.It Vibra16X and newer SB16/AWExx cards
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.Cd "pnp 1 0 os enable port0 0x220 irq0 5 drq0 1 drq1 3"
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.Pp
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Recently CreativeLabs has changed the codec (DSP) and the new one is
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somewhat different from the old one. The most apparent difference is
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the use of two 8-bit DMA channels, which seems to have broken our full
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duplex support. Maybe one can achieve full duplex by making use of the
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wavetable to play audio, but since this driver does not support the
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wavetable you have to stick with half duplex.
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.It SBPro and clones
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This is the default mode of operation for most other cards. We have
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only limited (and possibly buggy) support for them: 8-bit, half
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duplex, even if the hardware in some cases (e.g. ESS chips) might do more.
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.El
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.Pp
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.Sh DIAGNOSTICS AND TROUBLESHOOTING
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.Bl -tag -width 2m
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.It "This is XXX but LDN Y is disabled"
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.Pp
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This means that the bios has left the PnP device disabled, and you
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have to enable it manually booting with "-c" and giving the pnp
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configuration shown above.
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.It "pcmX: unit not configured, perhaps you want pcmY ?"
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This means that you are using the wrong unit. Generally this happens
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when you are using a PnP card without creating the symlinks to the
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correct unit. Re-create the symlinks (and possibly also the device
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entries) in the /dev directory to point to the right one.
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.It "timeout flushing dbuf_out ..."
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This means a problem in the configuration of the card (specifically,
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in the DMA channel) or (much less likely) in the driver, which has
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not recognized the card correctly. Check the DMA channel used for
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capture.
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.It capture does not work
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This usually happens when the input dma channel is misconfigured.
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.El
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.Sh BUGS
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Due to lack of documentation,
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SB16 support is not very good. Also, mixer support is not complete,
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and some features of your cards (e.g. global volume control) might not
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be supported on all devices.
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.Sh HISTORY
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The
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.Nm pcm
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device driver first appeared in
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.Fx 2.2.6
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.Sh AUTHORS
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The
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.Nm
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device driver and this manual page were written by
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.An Luigi Rizzo Aq luigi@iet.unipi.it
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