sound documentation for the snd_hda (Nvidia)

Alexander Leidinger Alexander at
Tue Nov 27 23:05:46 PST 2007

Quoting Chuck Robey <chuckr at> (from Mon, 26 Nov 2007  
12:23:38 -0500):

> Alexander Leidinger wrote:
>> Quoting Chuck Robey <chuckr at> (from Sun, 25 Nov 2007   
>> 14:59:01 -0500):
>>> Where do the developers of the HDA code hang out, on this list?  Is the
>>> snd_hda the current hda driver, and if so, where's the new code going
>>> to be?
>> The current HDA driver is in -current. RELENG_7 is on par (AFAIK).   
>> RELENG_6 is "close", but you are better of with RELENG_7 or HEAD.   
>> Yes this is the right list, and the only developer working on the   
>> HDA front and our sound infrastructure I'm aware of is Ariff (sorry  
>>  to the 2 others which work on the envy and creative drivers, but   
>> for this discussion you don't count ;-) ). He seems to be short of   
>> time ATM. You could try to catch him on #freebsd-azalia on freenode.
>> I'm not aware of a major rewrite in the HDA part. Ariff seems to be  
>>  working on something else:
> I was operating under the assumption that those comments from hdac.c,
> about the snd_hda driver badly needing a complete rewrite because it
> was insufficiently, well, bussed?  Yeah, bussed meant that code rework
> was ongoing.
> If you even know what that comment about the busses being less than
> they might be means, IF you could point me at any driver that you
> personally think shows a more *ideal* setup, it would at least make me
> aware of what's really wanted.  You don't need to describe it yourself,
> I know that'd be a major bore to do that for me, and I could probably
> learn as well by just reading code that illustrates what things
> *should* be.

AFAIK, the non-ideal part of the driver is not related to our  
soundsystem. I was told the HDA architecture allows more than just the  
normal sound output you get with, e.g. AC97 based soundcards. So I  
think the idea is to split up the driver specific part a little bit  
more, so that you can add more things later. So the parts you need to  
read are the HDA specs and get an idea what can be improved there.  
Graphically it's like this ATM:

|   FreeBSD kernel                       |
|                   +--------------+     |
|                   | sound subsys |     |
                    |   HDA code     |

And I think the goal is to get something like:
|   FreeBSD kernel                       |
|                   +--------------+     |
|                   | sound subsys |     |
                   |HDA bus/framework|
                    |     |        |
                 sound   ...     something_else

Hope this helps,

Kiss your keyboard goodbye!    Alexander @ PGP ID = B0063FE7       netchild @  : PGP ID = 72077137

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