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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 sound
device snd_hda
Alternatively, to load the driver as a module at boot time, place the following line in
loader.conf(5):
snd_hda_load="YES"
DESCRIPTION
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 snd_hda driver includes HDA bus controller driver (hdac), HDA codec driver (hdacc) and
HDA codecs audio functions bridge driver (hdaa) that allows the generic audio driver,
sound(4), to be used with this hardware. Only audio functions are supported by snd_hda.
Modem and other possible functions are not implemented.
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 Microsoft Universal Audio
Architecture (UAA) draft (revision 0.7b) for handling audio devices.
According to HDA and UAA specifications, depending on the number of HDA buses and codecs
present in system, their audio capabilities and BIOS provided configuration, the snd_hda
driver often provides several PCM audio devices. For example, one device for main rear 7.1
output and inputs, one device for independent headset connectors at front and one device for
SPDIF or HDMI audio input/output. The assignment of audio inputs and outputs may be tuned
with device.hints(5) or sysctl(8). The driver's verbose boot messages provide a lot of
information about the operation of the driver and present audio setup.
The default audio device may be tuned by setting the hw.snd.default_unit sysctl, as
described in sound(4), or explicitly specified in application settings.
Boot-time Configuration
The following variables are available at boot-time through the device.hints(5) file:
hint.hdac.%d.config Configures a range of possible controller options. Possible
values are: “64bit”, “dmapos”, “msi”. An option prefixed with
“no”, such as “nomsi”, will do the opposite and takes precedence.
Options can be separated by whitespace and commas.
hint.hdac.%d.msi Controls MSI (Message Signaled Interrupts) support.
hint.hdac.%d.cad%d.nid%d.config
Same as hint.hdaa.%d.nid%d.config
hint.hdaa.%d.config Configures a range of possible audio function options. Possible
values are: “eapdinv”, “ivref”, “ivref50”, “ivref80”, “ivref100”,
“fixedrate”, “forcestereo”, “ovref”, “ovref50”, “ovref80”,
“ovref100”, “senseinv”, “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.
The “eapdinv” option inverts External Amplifier Power Down
signal. The “fixedrate” denies all sampling rates except 48KHz.
The “forcestereo” denies mono playback/recording. The “senseinv”
option inverts jack sensing logic. The “ivrefX” and “ovrefX”
options control the voltage used to power external microphones.
dev.hdaa.%d.init_clear
Zero out the pin widget config setup by the system. Some systems
seem to have unuseable audio devices if the pin widgit
configuration is cleared. Set this value to 0 to accept the
default configuration values setup by the BIOS.
hint.hdaa.%d.gpio_config
Overrides audio function GPIO pins configuration set by BIOS.
May be specified as a set of space-separated “num=value” pairs,
where num is GPIO line number, and value is one of: “keep”,
“set”, “clear”, “disable” and “input”.
“GPIOs” are a codec's General Purpose I/O pins which system
integrators sometimes use to control external muters, amplifiers
and so on. If you have no sound, or sound volume is not
adequate, you may have to experiment a bit with the GPIO setup to
find the optimal setup for your system.
hint.hdaa.%d.nid%d.config
Overrides audio function pin configuration set by BIOS. May be
specified as a 32-bit hexadecimal value with a leading “0x”, or
as a set of space-separated “option=value” pairs.
hint.pcm.%d.rec.autosrc
Controls automatic recording source feature:
0 disabled,
1 once on attach,
2 enabled.
When enabled, driver will automatically set recording source of
the mixer to connected input using jack presence detection
statuses.
Pin configuration is the UAA driver's main source of information about codec usage. This
information is usually provided by the codec manufacturer and tuned by system integrators
for specific system requirements. The snd_hda driver allows users to override it to fix
integrator mistakes or to use the available codec in alternative ways (for example to get
stereo output and 2 inputs instead of a single 5.1 output).
The following options are supported:
as Association number. Associations are used to group individual pins to form a
complex multi-pin device. For example, to group 4 connectors for 7.1
input/output, or to treat several input connectors as sources for the same
input device. Association numbers can be specified as numeric values from 0
to 15. A value of 0 means disabled pin. A value of 15 is a set of
independent unassociated pins. Each association includes only pins of the
same direction (in/out) and is detected atomically (all pins or none). A
separate PCM audio device is created for every pair of input and output
associations.
seq Sequence number. A unique, per-association number used to order pins inside
the particular association. Sequence numbers can be specified as numeric
values from 0 to 15.
The sequence number 15 has a special meaning for output associations. Output
pins with this number and device type “Headphones” will duplicate (with
automatic mute if jack detection is supported) the first pin in that
association.
The sequence numbers 14 and 15 has a special meaning for input associations.
Their presence in association defines it as multiplexed or mixed
respectively. If none of them are present and there are more than one pin in
association, the association will provide multichannel input.
For multichannel input/output associations sequence numbers encode channel
pairs positions: 0 - Front, 1 - Center/LFE, 2 - Back, 3 - Front Wide Center,
4 - Side. Standard combinations are: (0) - Stereo; (0, 2), (0, 4) - Quadro;
(0, 1, 2), (0, 1, 4) - 5.1; (0, 1, 2, 4) - 7.1.
device Device type. Can be specified as a number from 0 to 15 or as a name:
“Line-out”, “Speaker”, “Headphones,” “CD”, “SPDIF-out”, “Digital-out”,
“Modem-line”, “Modem-handset”, “Line-in”, “AUX”, “Mic”, “Telephony”,
“SPDIF-in”, “Digital-in”, “Res.E”, or “Other”. The device type also
describes the pin direction (in/out). For example, “CD” always means an
input pin, while “Headphones” always means an output.
conn Connection type. Can be specified as a number from 0 to 3. The connection
type can also be specified as one of the special names “Jack”, “None”,
“Fixed”, or “Both”. Pins with a connection type of “None” are disabled.
ctype Connector physical type. Can be specified as a number from 0 to 15. This is
a reference only value. It is ignored by the snd_hda driver.
color Connector color. Can be specified as a number from 0 to 15 or as one of the
names “Unknown”, “Black”, “Grey”, “Blue”, “Green”, “Red”, “Orange”, “Yellow”,
“Purple”, “Pink”, “Res.A”, “Res.B”, “Res.C”, “Res.D”, “White”, or “Other”.
This is a reference only value. It is ignored by the snd_hda driver.
loc Connector physical location. Can be specified as a number from 0 to 63.
This is a reference only value. It is ignored by the snd_hda driver.
misc Misc bits. Can be specified as a number from 0 to 15. Bit 0 has a special
meaning. When set it means that jack detection is not implemented in
hardware.
Runtime Configuration
The following sysctl(8) variables are available in addition to those available to all
sound(4) devices:
dev.hdac.%d.pindump Setting this to a non-zero value dumps the current pin
configuration, main capabilities and jack sense status of
all audio functions on the controller to console and
syslog.
dev.hdac.%d.polling Enables polling mode. In this mode the driver operates by
querying the device state on timer ticks using callout(9)
instead of interrupts. 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.
dev.hdaa.%d.config Run-time equivalent of the hint.hdaa.%d.config tunable.
dev.hdaa.%d.gpi_state Current state of GPI lines.
dev.hdaa.%d.gpio_state Current state of GPIO lines.
dev.hdaa.%d.gpio_config Run-time equivalent of the hint.hdaa.%d.gpio.config
tunable.
dev.hdaa.%d.gpo_state Current state of GPO lines.
dev.hdaa.%d.nid%d_config Run-time equivalent of the hint.hdaa.%d.nid%d.config
tunable.
dev.hdaa.%d.nid%d_original Original pin configuration written by BIOS.
dev.hdaa.%d.reconfig Setting this to a non-zero value makes driver to destroy
existing pcm devices and process new pins configuration
set via dev.hdaa.%d.nid%d_config.
dev.pcm.%d.play.32bit, dev.pcm.%d.rec.32bit
HDA controller uses 32bit representation for all samples
of more then 16 bits. These variables allow to specify
how many bits of these 32 should be used by CODEC.
Depending on codec capabilities, possible values are 20,
24 and 32 bit. The default value is 24.
dev.pcm.%d.rec.autosrc Run-time equivalent of the hint.pcm.%d.rec.autosrc
tunable.
EXAMPLES
Taking HP Compaq DX2300 with Realtek ALC888 HDA codec for example. This system has two
audio connectors on a front side, three audio connectors on a rear side and one internal
speaker. According to verbose driver output and the codec datasheet, this codec has five
stereo DACs and two stereo ADCs, all of them are routable to any codec pin (external
connector). All codec pins are reversible (could be configured either as input or output).
So high codec uniformity and flexibility allow driver to configure it in many different
ways, depending on requested pins usage described by pins configuration. The driver reports
such default pin configuration when verbose messages enabled:
hdaa0: nid 0x as seq device conn jack loc color misc
hdaa0: 20 01014020 2 0 Line-out Jack 1/8 Rear Green 0
hdaa0: 21 99130110 1 0 Speaker Fixed ATAPI Onboard Unknown 1
hdaa0: 22 411111f0 15 0 Speaker None 1/8 Rear Black 1 DISA
hdaa0: 23 411111f0 15 0 Speaker None 1/8 Rear Black 1 DISA
hdaa0: 24 01a19830 3 0 Mic Jack 1/8 Rear Pink 8
hdaa0: 25 02a1983f 3 15 Mic Jack 1/8 Front Pink 8
hdaa0: 26 01813031 3 1 Line-in Jack 1/8 Rear Blue 0
hdaa0: 27 0221401f 1 15 Headphones Jack 1/8 Front Green 0
hdaa0: 28 411111f0 15 0 Speaker None 1/8 Rear Black 1 DISA
hdaa0: 30 411111f0 15 0 Speaker None 1/8 Rear Black 1 DISA
hdaa0: 31 411111f0 15 0 Speaker None 1/8 Rear Black 1 DISA
Here we can see, that the nodes with ID (nid) 25 and 27 are front panel connectors (Jack,
Front), nids 20, 24 and 26 are rear panel connectors (Jack, Rear) and nid 21 is a built-in
speaker (Fixed, Onboard). Pins with nids 22, 23, 28, 30 and 31 will be disabled by driver
due to "None" connectivity. So the pin count and description matches to connectors that we
have.
Using association (as) and sequence (seq) fields values pins are grouped into 3
associations:
hdaa0: Association 0 (1) out:
hdaa0: Pin nid=21 seq=0
hdaa0: Pin nid=27 seq=15
hdaa0: Association 1 (2) out:
hdaa0: Pin nid=20 seq=0
hdaa0: Association 2 (3) in:
hdaa0: Pin nid=24 seq=0
hdaa0: Pin nid=26 seq=1
hdaa0: Pin nid=25 seq=15
Each pcm(4) device uses two associations: one for playback and one for recording.
Associations processed and assigned to pcm(4) devices in increasing numerical order. In
this case association #0 (1) will become pcm0 device playback, using the internal speakers
and Headphones jack with speaker automute on the headphones jack connection. Association #1
(2) will become pcm1 playback, using the Line-out jack. Association #2 (3) will become pcm0
recording, using the external microphones and the Line-in jack.
The snd_hda driver provides extensive verbose messages to diagnose its operation logic and
describe its current codec configuration.
Using device.hints(5) it is possible to modify the configuration of the existing pins,
allowing a broad range of different audio setups. Here are a few examples of some setups
possible for this particular hardware:
Example 1
Setting the device.hints(5) options
hint.hdac.0.cad0.nid20.config="as=1"
hint.hdac.0.cad0.nid21.config="as=2"
will swap line-out and speaker functions. So the pcm0 device will play to the line-out and
headphones jacks. Line-out will be muted on the headphones jack connection. Recording on
pcm0 will go from two external microphones and line-in jacks. pcm1 playback will go to the
internal speaker.
Example 2
Setting the device.hints(5) options
hint.hdac.0.cad0.nid20.config="as=1 seq=15 device=Headphones"
hint.hdac.0.cad0.nid27.config="as=2 seq=0"
hint.hdac.0.cad0.nid25.config="as=4 seq=0"
will split the headphones and one of the microphones to a separate device. The pcm0 device
will play to the internal speaker and to the line-out jack, with speaker automute on the
line-out jack connection. Recording on pcm0 will use input from one external microphone and
the line-in jacks. The pcm1 device will be completely dedicated to a headset (headphones
and mic) connected to the front connectors.
Example 3
Setting the device.hints(5) options
hint.hdac.0.cad0.nid20.config="as=1 seq=0"
hint.hdac.0.cad0.nid26.config="as=2 seq=0"
hint.hdac.0.cad0.nid27.config="as=3 seq=0"
hint.hdac.0.cad0.nid25.config="as=4 seq=0"
hint.hdac.0.cad0.nid24.config="as=5 seq=0 device=Line-out"
hint.hdac.0.cad0.nid21.config="as=6 seq=0"
will give 4 independent devices: pcm0 (line-out and line-in), pcm1 (headphones and mic),
pcm2 (additional line-out via retasked rear mic jack), and pcm3 (internal speaker).
Example 4
Setting the device.hints(5) options
hint.hdac.0.cad0.nid20.config="as=1 seq=0"
hint.hdac.0.cad0.nid24.config="as=1 seq=1 device=Line-out"
hint.hdac.0.cad0.nid26.config="as=1 seq=2 device=Line-out"
hint.hdac.0.cad0.nid21.config="as=2 seq=0"
will give 2 devices: pcm0 for 5.1 playback via 3 rear connectors (line-out and retasked mic
and line-in) and headset (headphones and mic) at front connectors. pcm1 for internal
speaker playback. On headphones connection rear connectors will be muted.
MIXER CONTROLS
Depending on codec configuration, these controls and signal sources could be reported to
sound(4):
vol overall output level (volume)
rec overall recording level
igain input-to-output monitoring loopback level
ogain external amplifier control
pcm PCM playback
mix input mix
mic first external or second internal microphone input
monitor first internal or second external microphone input
line, line1, line2, line3
analog (line) inputs
dig1, dig2, dig3
digital (S/PDIF, HDMI or DisplayPort) inputs
cd CD input
speaker PC speaker input
phin, phout, radio, video
other random inputs
Controls have different precision. Some could be just an on/off triggers. Most of controls
use logarithmic scale.
HARDWARE
The snd_hda driver supports controllers having PCI class 4 (multimedia) and subclass 3
(HDA), compatible with Intel HDA specification.
The snd_hda driver supports more than two hundred different controllers and CODECs. There
is no sense to list all of them here, as in most cases specific CODEC configuration and
wiring are more important then type of the CODEC itself.
SEE ALSO
snd_ich(4), sound(4), device.hints(5), loader.conf(5), sysctl(8)
HISTORY
The snd_hda device driver first appeared in FreeBSD 6.3.
AUTHORS
The snd_hda driver was written by Stephane E. Potvin <sepotvin@videotron.ca>, Ariff Abdullah
<ariff@FreeBSD.org> and Alexander Motin <mav@FreeBSD.org>. This manual page was written by
Joel Dahl <joel@FreeBSD.org>, Alexander Motin <mav@FreeBSD.org> and Giorgos Keramidas
<keramida@FreeBSD.org>.
BUGS
Some Hardware/OEM vendors tend to screw up BIOS settings or use custom unusual CODEC wiring
that create problems to the driver. This may result in missing pcm devices, or a state
where the snd_hda driver seems to attach and work, but no sound is played. Some cases can
be solved by tuning loader.conf variables. But before trying to fix problem that way, make
sure that there really is a problem and that the PCM audio device in use really corresponds
to the expected audio connector.
Some vendors use non-standardized General Purpose I/O (GPIO) pins of the codec to control
external amplifiers. In some cases setting a combination of GPIO bits may be needed to make
sound work on a specific device.
HDMI and DisplayPort audio may also require support from video driver.