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SND_HDA(4)	       FreeBSD Kernel Interfaces Manual		    SND_HDA(4)

     snd_hda --	Intel High Definition Audio bridge device driver

     To	compile	this driver into the kernel, place the following lines in your
     kernel configuration file:

	   device sound
	   device snd_hda

     Alternatively, to load the	driver as a module at boot time, place the
     following line in loader.conf(5):


     The snd_hda bridge	device driver allows the generic audio driver,
     sound(4), to attach to Intel High Definition Audio	devices.  The snd_hda
     driver supports hardware that conforms with revision 1.0 of the Intel
     High Definition Audio specification and tries to behave much like the Mi-
     crosoft Universal Audio Architecture (UAA)	draft (revision	0.7b) for han-
     dling audio devices.  HDA acts like a primary bus,	similar	to miibus(4),
     for handling various child	buses such as audio, modem and HDMI (High Def-
     inition Multimedia	Interface).  Only audio	is implemented in the snd_hda

     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	compo-
     nents.  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.hints(5) file:

	   hint.pcm.%d.config  Configures a range of possible options.	Possi-
			       ble 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 fac-
			       ing weird interrupt problems or if the device
			       cannot generate interrupts at all.

     The snd_hda driver	supports the following audio chipsets:

     +o	 ATI SB450
     +o	 ATI SB600
     +o	 Intel 631x/632xESB
     +o	 Intel 82801F
     +o	 Intel 82801G
     +o	 Intel 82801H
     +o	 nVidia	MCP51
     +o	 nVidia	MCP55
     +o	 nVidia	MCP61A
     +o	 nVidia	MCP61B
     +o	 nVidia	MCP65A
     +o	 nVidia	MCP65B
     +o	 SiS 966
     +o	 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:

     +o	 Analog	Device AD1981HD
     +o	 Analog	Device AD1983
     +o	 Analog	Device AD1986A
     +o	 Analog	Device AD1988
     +o	 CMedia	CMI9880
     +o	 Conexant Venice
     +o	 Conexant Waikiki
     +o	 Realtek ALC260
     +o	 Realtek ALC262
     +o	 Realtek ALC861
     +o	 Realtek ALC861VD
     +o	 Realtek ALC880
     +o	 Realtek ALC882
     +o	 Realtek ALC883
     +o	 Realtek ALC885
     +o	 Realtek ALC888
     +o	 Sigmatel STAC9220
     +o	 Sigmatel STAC9220D/9223D
     +o	 Sigmatel STAC9221
     +o	 Sigmatel STAC9221D
     +o	 Sigmatel STAC9227
     +o	 Sigmatel STAC9271D
     +o	 VIA VT1708
     +o	 VIA VT1709

     sound(4), device.hints(5),	loader.conf(5),	sysctl(8)

     The snd_hda device	driver first appeared in FreeBSD 6.3.

     The snd_hda driver	was written by Stephane	E. Potvin
     <> and Ariff Abdullah	<>.  This
     manual page was written by	Joel Dahl <>.

     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 snd_hda driver	useless, which usually results in a state where	the
     snd_hda driver seems to attach and	work, but without any sound.

FreeBSD	6.3			  May 5, 2007			   FreeBSD 6.3


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