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SND_HDA(4)		 BSD 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 ad-
     vantages, 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 op-
			       tion prefixed with "no",	such as	"nofixedrate",
			       will do the opposite and	takes precedence.  Op-
			       tions can be separated by whitespace and	com-

   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 op-
			       erates 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	 Intel 82801I
     +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	Devices	AD1981HD
     +o	 Analog	Devices	AD1983
     +o	 Analog	Devices	AD1986A
     +o	 Analog	Devices	AD1988
     +o	 Analog	Devices	AD1988B
     +o	 CMedia	CMI9880
     +o	 Conexant Venice
     +o	 Conexant Waikiki
     +o	 Realtek ALC260
     +o	 Realtek ALC262
     +o	 Realtek ALC268
     +o	 Realtek ALC660
     +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.

BSD				 July 14, 2007				   BSD


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