[LAU] Small instrument hardware module

Kazakore dj_kaza at hotmail.com
Wed Oct 22 04:30:27 UTC 2014

On 22/10/14 11:36, Len Ovens wrote:
> On Wed, 22 Oct 2014, Kazakore wrote:
>> This is also what I was lead to believe. snd_hda_intel covers a fair 
>> range of different
>> chips, each of which has its own characteristics and so there is no 
>> single answer to the
>> original question. Pretty sure both my last two laptops were reported 
>> as snd_hda_intel
>> and know they were definitely different sound chips! (Although 
>> offhand couldn't tell you
>> what...)
>> "Like AC'97, HD Audio is a specification that defines the 
>> architecture, link frame
>> format, and programming interfaces used by the controller on the PCI 
>> bus and by the
>> codec on the other side of the link. Implementations of the host 
>> controller are
>> available from at least Intel, Nvidia, and AMD." [1]
> Ok, that sounds prettier than what I said :)  the reason I called it a 
> bus though is that one HDA interface seems to be able to handle a 
> number of physical audio devices. Each of which can have a different 
> bit depth and sample rate at the same time (say what?) so that the 
> user could have a telephone handset hooked up to the interface at 
> 32k/8bits while listening to/watching a high definition video. I don't 
> know that Linux can handle this though. (or windows for that matter) I 
> am just repeating some of the stuff I remember from reading though 
> some of the very long and involved Intel Doc.
>> Not sure if there is a mistake on the page or if my laptop actually 
>> has both of these
>> for something?? [2]
>> Intel 7 Series/C210 Series Chipset Family High Definition Audio 
>> Controller
>> Intel Panther Point High Definition Audio Controller
> It may have both on the same PCI IF even. cat /proc/interupts should 
> tell I think. As a note. On my netbook, the audio IF can run at a 
> number of sample rates with no problems, but my internal mic which 
> shows up on the same ALSA device, can only run at 48k. That is the ADC 
> for the internal mic only runs at 48k and if the rest of the internal 
> audio (internal speakers, line in/out plugs, are set to 44.1k, those 
> i/os will be fine, but the internal mic will have a periodic click as 
> the 44.1 and 48k sample rates align and cycle past each other. The 
> click goes away if the AI is set to 48K.
> Be sure to look at the variety of HDA IF types the ALSA driver handles 
> and all of the settings that can be given to the HDA driver. It is 
> quite a long list.

I did a very small amount of research after my last post and it seems 
the HDA chipset controller is often the same as the South Bridge. Only 
my old P4 desktop it was the ICH6 I think, (or was that ICH5 and AC97?? 
can't remember now...) and on this laptop I guess the 7 relates to 
something similar to the ICH7 but for laptops.

But yeah there is a ~250 page pdf on the v1 docs which can be found 
online (in fact it's linked from the Wikipedia article I linked to 
earlier.) Not read through it myself. But from the desctription I can 
understand why you say Bus. But a bus wouldn't generally include codecs 
and things, so it's more than just the bus really isn't it? Nearly a 
whole protocol really...

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