[alsa-devel] [PATCH] ALSA: HDA: Add jack detection for HDMI

Stephen Warren swarren at nvidia.com
Mon May 23 17:29:22 CEST 2011

David Henningsson wrote at Saturday, May 21, 2011 12:26 AM:
> On 2011-05-20 23:59, Stephen Warren wrote:
> > David Henningsson wrote at Tuesday, May 17, 2011 7:47 AM:
> >> Just as for headphones and microphone jacks, this patch adds reporting
> >> of HDMI jack status through the input layer.
> >
> > Some of our older HW (MCP6x, MCP7x chipsets) doesn't support unsolicited
> > responses, nor PD/ELDV/ELD data. If PulseAudio is updated to listen to
> > these new jack events on kernels where the input files are present,
> > that'll presumably cause it never to allow use of the HDMI sinks on those
> > chipsets. I don't know if other vendors have this issue or not.
> Ok, thanks for the input (no pun intended ;-) ). If they support
> presence detect, we could create a polling loop. Otherwise, don't create
> the jack.

There's no unsolicited response, nor is there any way to read any of the
PD/ELD data as far as I know, nor any way for the graphics driver to pass
it into the audio HW I presume.

> Is this autodetectable or do we have to quirk it?

The relevant NVIDIA chips have custom .patch functions in
snd_hda_preset_hdmi[], which end up not calling snd_hda_eld_proc_new()
for the pins in question. I note that many of the ATI/AMD codecs are in
the same boat here. Presumably, that function sets up some data structure
that could easily be keyed off of.


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