[OLPC-devel] Re: ALSA interface for the analog input

[Jaya Kumar]

On 7/6/06, Jim Gettys <jg at laptop.org> wrote:
> Jaya,
>
> I know it will be a little bit until we have the embedded controller
> code for the analog input on the codec done.
>
> I was wondering what sort of ALSA interface should exist (if any) for
> such a feature, or whether the interface for the analog input control
> should be elsewhere.

I would recommend using mixer controls. This surfaces the capability
of switching into DC sensor mode (turning off Vrefout and disabling
the high pass filter Miller found) to user level applications via the
standard alsa mixer api. That's how other AC97 codecs and other AC97
codec specific features are handled. Scripted applications can call
amixer directly to switch into that mode if they wanted to avoid
directly pulling in alsa libs.

By the way, as I had promised before, the patch that does the above is
already in ALSA. :-)

http://git.kernel.org/git/?p=linux/kernel/git/perex/alsa-current.git;a=commit;h=02856b5684677b74095069c3be4774c2992e4fdc

Thanks,
jaya