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HDAUDIO(4) NetBSD Kernel Interfaces Manual HDAUDIO(4)
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hdaudio -- High Definition Audio device driver
hdaudio* at pci? dev ? function ?
hdafg* at hdaudiobus?
audio* at audiobus?
The hdaudio device driver is expected to support any PCI device which is
compliant to the High Definition Audio Specification 1.0. It is a
replacement for azalia(4). It was written from scratch following the
Intel HD Audio and Microsoft Universal Audio Architecture specifications.
The driver consists of two interlinked components, which reflects the
hardware design. The hdaudio component interfaces with a PCI/PCIe bus
and provides an hdaudiobus(4) onto which different function groups
attach. Each function group (e.g. audio, vendor-specific modem) is
exported as a separate child device of the hdaudio controller. Audio
function groups (a.k.a. audio codec) are exported as hdafg(4) devices.
Audio codecs are available from a number of manufacturers and are made up
of a number of widgets (e.g. audio mixer, output pin, analog-to-digital
converter). The way the widgets are interlinked varies significantly
between implementations. The tree of widgets must be parsed and mapped
to mixer(4) controls. As part of this process, loops in the inter-codec
links must be detected and muted, bi-directional pins must be set up
appropriately and the locations of pins determined. Unlike the azalia(4)
driver (which tends to generate a large number of unclearly named
mixer(4) controls), hdaudio works backwards by starting with a list of
desired, consistent and compatible mixer(4) controls and configuring/dis-
covering appropriate widget link routes to fit.
By following the published mechanisms for common implementations of wid-
get parsing, it is expected that nearly all High Definition Audio devices
will be supported without requiring per-device quirks.
audio(4), mixer(4), pci(4), hdaudioctl(8),
The hdaudio device driver appeared in NetBSD 5.1.
The hdaudio driver was written by Jared McNeill <jmcneill@NetBSD.org>
under contract by
Precedence Technologies Ltd <http://www.precedence.co.uk/>. The UAA-com-
pliant widget parser is derived from the FreeBSD snd_hda(4) driver.
The following items are not yet implemented:
· Improve power management support when driver is idle
· Add support for non-PCM output formats
· Handle unsolicited RIRB messages
· Modem function groups
NetBSD 5.1 September 28, 2010 NetBSD 5.1