xref: /freebsd/share/man/man4/pcm.4 (revision daf1cffce2e07931f27c6c6998652e90df6ba87e)
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2.\" Copyright (c) 1998, Luigi Rizzo
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26.\" $FreeBSD$
27.\"
28.Dd June 3, 1998
29.Dt PCM 4
30.Os FreeBSD
31.Sh NAME
32.Nm pcm
33.Nd FreeBSD PCM audio device driver
34.Sh SYNOPSIS
35For a card with bridge driver support, and a PnP card:
36.Cd "device pcm"
37.Pp
38For a card without bridge driver support, and a non-PnP card:
39.Cd "device pcm0 at isa? port? irq 5 drq 1 flags 0x15"
40.Sh DESCRIPTION
41The
42.Nm
43driver provides support for PCM audio play and capture. This driver
44also supports various PCI and WSS/MSS compatible ISA sound cards, and
45AC97 mixer. True full duplex operation is available on most cards.
46.Pp
47If your sound card is supported by a bridge driver,
48.Nm
49driver works
50in conjunction with the bridge driver.
51.Pp
52Apart from the usual parameters, the flags field is used to specify
53the secondary DMA channel (generally used for capture in full duplex
54cards). Flags are set to 0 for cards not using a secondary DMA
55channel, or to 0x10 + C to specify channel C.
56.Pp
57The driver works best with WSS/MSS cards, which have a very clean
58architecture and an orthogonal set of features. They also happen to be
59among the cheapest audio cards on the market.
60.Pp
61The driver does its best to recognize the installed harware and drive
62it correctly, so that you don't have to give too many details in the
63kernel config files. For PCI and ISA PnP cards this is actually easy
64since they identify themselves. For legacy ISA cards, the driver looks
65for MSS cards at addresses 0x530 and 0x604 (obviously, unless overridden
66in the kernel config file by specifying an address).
67
68.Sh IOCTL
69The driver supports most of the Voxware ioctls(), and most
70applications work unmodified (including popular mpeg players and linux
71binaries). A few
72differences exist (the most important one is the ability to use
73memory-mapped access to the audio buffers). As a consequence, some
74applications may need to be recompiled with a slightly modified
75audio module.  See /usr/include/sys/soundcard.h for a complete
76list of the supported ioctls.
77
78.Sh SUPPORTED CARDS
79.Pp
80Below we include a list of supported codecs/cards. If your sound card
81is not listed here, it may be supported by a bridge driver.
82
83.Bl -tag -width 2m  % begin list
84.It CS4237, CS4236, CS4232, CS4231 (ISA)
85.Pp
86All these cards work perfectly in full duplex using the MSS mode.
87This chipset is used, among others, on the A/Open AW35 and AW32, on
88some Intel motherboards, and (the CS4231) on some non-PnP cards.
89.Pp
90The CS4232 is reported as buggy in the Voxware documentation but
91I am not sure if this is true. On one of my Intel motherboards,
92capture does not work simply because the capture DMA channel is
93not wired to the ISA DMA controller.
94
95.It Yamaha OPL-SAx (ISA)
96.Pp
97Works perfectly in all modes. This chip is used in several PnP cards,
98but also (in non-PnP mode) on motherboards and laptops (e.g. the
99Toshiba Libretto).
100
101.It OPTi931 (ISA)
102.Pp
103The chip is buggy, but the driver has many workarounds to make it work
104in full duplex because for some time these were the only full duplex
105cards I could find. u-law formats uses U8 format internally because of
106a bug in the chip.
107
108.It Trident 4DWave DX/NX (PCI)
109.Pp
110.It ENSONIQ AudioPCI ES1370/1371 (PCI)
111.Pp
112Creative Labs SoundBlaster PCI is supported as well.
113
114.It NeoMagic 256AV/ZX (PCI)
115.Pp
116.El
117.Pp
118.Sh DIAGNOSTICS AND TROUBLESHOOTING
119.Bl -tag -width 2m
120.It ac97: dac not ready
121AC97 codec is not likely to be accompanied with the sound card.
122
123.It unsupported subdevice XX
124A device node is not created properly.
125
126.El
127.Sh BUGS
128Some features of your cards (e.g. global volume control) might not
129be supported on all devices.
130.Sh HISTORY
131The
132.Nm
133device driver first appeared in
134.Fx 2.2.6 ,
135rewritten in
136.Fx 4.0 .
137.Sh SEE ALSO
138.Xr sbc 4
139.Xr gusc 4
140.Xr csa 4
141.Sh AUTHORS
142.An Luigi Rizzo Aq luigi@iet.unipi.it
143initially wrote the .Nm device driver and this manual page.
144.An Cameron Grant Aq gandalf@vilnya.demon.co.uk
145totally revised the device driver.
146.An Seigo Tanimura Aq tanimura@r.dl.itc.u-tokyo.ac.jp
147revised this manual page.
148