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):
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
“ivref
X”
and
“ovref
X”
options control the voltage used to power external microphones.
- 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
”.
“GPIO
s” 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¶
sound(4),
snd_ich(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.