.\"	$NetBSD: auich.4,v 1.25 2016/10/16 05:26:20 wiz Exp $
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.\" by Jason R. Thorpe.
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.Dd October 13, 2016
.Dt AUICH 4
.Os
.Sh NAME
.Nm auich
.Nd Intel I/O Controller Hub integrated AC'97 audio device driver
.Sh SYNOPSIS
.Cd "auich* at pci? dev ? function ?"
.Cd "audio* at audiobus?"
.Sh DESCRIPTION
The
.Nm
device driver supports the integrated AC'97 audio controller
of the Intel I/O Controller Hub.
Supported chipsets include the i82801AA (ICH), i82801AB (ICH0),
i82801BA (ICH2), i82440MX, i82801CA (ICH3), i82801DB (ICH4), i82801EB (ICH5),
i82801FB (ICH6), i82801GB/GR (ICH7), and Intel 6300ESB.
The driver also supports SiS 7012, nForce MCP, nForce2 MCP-T,
nForce3 MCP-T, nForce3 250 MCP-T, nForce4, and AMD 8111.
.Pp
The driver provides the following
.Xr sysctl 8
read/write variable (when hardware support is available):
.Bl -tag -width Ds
.It Va hw.auich0.ac97rate
Link rate of the device in Hz.
The driver automatically measures and
calculates the correct rate so you usually don't need to change
this.
There is, however, a chance that the driver miscalculates the
rate especially on an emulated hardware, resulting in an incorrect
playback pitch.
When this happens you need to manually set this
variable to the correct value.
Try
.Li 48000
if you don't know the correct value as it is the default link rate.
.Sh SEE ALSO
.Xr ac97 4 ,
.Xr audio 4 ,
.Xr pci 4 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
device driver appeared in
.Nx 1.6 .
.Sh BUGS
The
.Sq microphone
input DMA channel is not currently supported.