Re: [9fans] PWM and audio drivers for Raspberry Pi

[dante <subscriptions@posteo.eu>]

Hi Pedro,

That's super-cool, thanks!

Please consider submitting the patch through the right channels.
Since I'm new here, I am not sure if this is correct, but here is what
I found out:

1. as a patch(1) to the contributors. No idea if geoff or jmk are still
working there:
     http://plan9.bell-labs.com/wiki/plan9/How_to_contribute/

2. ask David du Colombier to accept and publish your patch:
     http://www.9legacy.org

Cheers,
Dante

On 23.08.2014 11:32, Pedro Coutin wrote:
> Hello everyone,
>
> I made a working audio driver for the Raspberry Pi by using the
> chipset's
> PWM device directly.
>
> The sound quality seems pretty acceptable to me.  I managed to play
> music
> and the Doom port from 9front with it.
>
> Since it uses the PWM device, it only works for the TRS stereo jack.
> I
> believe that the most sensible way to make HDMI audio work is to
> make a VCHI(Q) driver, and then an audio driver that interfaces with
> that. There's very little, if any, documentation available on this and
> the Linux kernel code for it is pretty huge.
>
> Tarball with changed files:
> http://acsweb.ucsd.edu/~pcoutin/bcm-audio.tgz
>
> Repository:
> https://bitbucket.com/pcoutin/9pi-audio
>
> Man page for PWM device:
> http://acsweb.ucsd.edu/~pcoutin/bcmpwm.html
>
> I guess I could extend the PWM driver so that the two channels can be
> enabled/disabled separately.