SND_HDA(4) FreeBSD Kernel Interfaces Manual SND_HDA(4)
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 unusable
audio devices if the pin widget 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.
HARDWARE
The snd_hda driver supports PCI class 04h (multimedia), subclass 03h
(HDA) audio controllers and codecs compatible with the Intel High
Definition Audio 1.0 specification.
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.
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.
FreeBSD 15.1-STABLE-HBSD January 20, 2025 SND_HDA(4)