[alsa-devel] HD-Audio Codec ALC888: Realtek Defined Registers and Digital Microphone
sebastian.konopka at ph.tum.de
Thu Oct 15 11:57:14 CEST 2009
Hello everybody on alsa-devel,
I'm adding a new model to the patch_realtek.c file that supports all
features my alc888-codec together with the laptop hardware
offers. Everything works fine and can be used through alsa, except two
things, because I did not find any usable information on them:
1. My laptop has an built-in digital microphone, that is connected to
this codec according to the information I can get when using
windows. The ALC888 datasheet shows that there are pins for digital
microphone support. Thus I assume that they are used for the
microphone. Those pins are share their functionality with GPIO pins:
GPIO0/DMIC-CLK and GPIO1/DMIC-DATA.
Unfortunally the datasheet does not provide further information on
how to switch between GPIO and DMIC mode of those pins. Furthermore
there is no information where the digital data can be found and how
to transfer them over the HDA-Bus to the application.
Does anybody have additional information on how to use digital
microphones on realtek codecs?
2. Perhaps enabling the digital microphone is related to the so-called
"Realtek Defined Registers" that can be found on NID=0x20 as
processing coefficients. Furthermore the alc888 supports additional
features like equalizer or echo-cancellation, etc. that can be
controlled by these registers, as I suppose.
Does anybody have information how what these registers and their
contents mean? The datasheet does not provide any information.
I hope you can help me.
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