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snd_hda (4)
>> snd_hda (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
snd_hda
- Intel High Definition Audio bridge device driver
SYNOPSIS
To compile this driver into the kernel, place the following lines in your
kernel configuration file:
device sounddevice snd_hda
Alternatively, to load the driver as a module at boot time, place the
following line in
loader.conf5:
snd_hda_load="YES"
DESCRIPTION
The
bridge device driver allows the generic audio driver,
sound(4),
to attach to Intel High Definition Audio devices.
The
driver supports hardware that conforms with revision 1.0 of the Intel High
Definition Audio specification and tries to behave much like the Microsoft
Universal Audio Architecture (UAA) draft (revision 0.7b) for handling audio
devices.
HDA acts like a primary bus, similar to
miibus(4),
for handling various child buses such as audio, modem and HDMI (High Definition
Multimedia Interface).
Only audio is implemented in the
driver.
The High Definition (HD) Audio specification was developed by Intel as the
logical successor of the old AC'97 specification and has several advantages,
such as higher bandwidth which allows more channels and more detailed formats,
support for several logical audio devices, and general purpose DMA channels.
The HDA specification defines the register-level interface, physical link
characteristics, codec programming models, and codec architectural components.
This specification is intended for both device driver developers and hardware
component designers.
Boot-time Configuration
The following variables are available at boot-time through the
device.hints5
file:
hint.pcm.%d.config
Configures a range of possible options.
Possible values are:
``dmapos
''
``eapdinv
''
``gpio0
''
``gpio1
''
``gpio2
''
``gpio3
''
``gpio4
''
``gpio5
''
``gpio6
''
``gpio7
''
``gpioflush
''
``ivref
''
``ivref50
''
``ivref80
''
``ivref100
''
``fixedrate
''
``forcestereo
''
``ovref
''
``ovref50
''
``ovref80
''
``ovref100
''
``softpcmvol
''
and
``vref
''
An option prefixed with
``no
''
such as
``nofixedrate
''
will do the opposite and takes precedence.
Options can be separated by whitespace and commas.
Runtime Configuration
The following
sysctl(8)
variables are available in addition to those available to all
sound(4)
devices:
dev.pcm.%d.polling
Experimental polling mode, where the driver operates by querying the device
state on each tick using
callout(9).
Polling is disabled by default.
Do not enable it unless you are facing weird interrupt problems or if the
device cannot generate interrupts at all.
HARDWARE
The
driver supports the following audio chipsets:
ATI SB450
ATI SB600
Intel 631x/632xESB
Intel 82801F
Intel 82801G
Intel 82801H
Intel 82801I
nVidia MCP51
nVidia MCP55
nVidia MCP61A
nVidia MCP61B
nVidia MCP65A
nVidia MCP65B
SiS 966
VIA VT8251/8237A
Generic audio chipsets compatible with the Intel HDA specification should work,
but have not been verified yet.
The following codecs have been verified to work:
There are a couple of missing features, such as support for Digital
S/PDIF and multichannel output.
A few Hardware/OEM vendors tend to screw up BIOS settings, thus
rendering the
driver useless, which usually results in a state where the
driver seems to attach and work, but without any sound.
