[alsa-devel] DP MST audio support

[Dave Airlie]

On 12 May 2015 at 11:50, Dave Airlie <airlied at gmail.com> wrote:
> Hi,
>
> So I have a branch that makes no sound,
> http://cgit.freedesktop.org/~airlied/linux/log/?h=dp-mst-audio
>
> and I'm not sure where I need to turn to next,
>
> The Intel docs I've read are kinda vague, assuming you know lots of
> things I clearly don't.
>
> so in theory my branch, sets up the SDP stream to the monitor in the
> payload creation,
> enables the codec in the intel GPU driver, and passes the ELD to the
> audio driver.
>
> The audio driver uses the device list to get the presence/valid bits
> per device, and manages to retrieve the ELD. I even create ELD files
> in /proc/asound/HDMI/ that have sensible values in them
>
> So it looks like I'm just missing some routing somewhere, most likely
> in the audio driver, then again I  could be missing a lot more than
> that.
>
> Just looking for any ideas or knowledge people may have locked in
> their brains or inside their firewalls.

Okay the branch now has audio on my test setup,

I've had to hack out the intel_not_share_assigned_cvt function
it appears to do bad things, I set pin 6 to connection 0 (pin 2), the later
sets on pin 5/7 to connection 1 by that function seems to reprogram pin 6.

I'm guessing the connection is assigned to a device not a pin in the new hw,
and the same device is routed via pin 5/7 so I end up trashing it.

my test setup is a Haswell Lenovo t440s + docking station + Dell U2410.

Dave.