[Bug 101583] [KBL] intel NUC6CAYH no LSPCON HDMI audio output

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=101583

--- Comment #33 from Joseph Nuzman <jnuzman at gmail.com> ---
(In reply to Jani Nikula from comment #32)
> The original reason for that has been clear all along: With LSPCON the port
> looks like DP to the driver, but the ELD comes all the way from the display,
> which is HDMI.
> 
> So I didn't track down all the paths in your description or your patch, but
> is this really not enough:
> 
> https://bugs.freedesktop.org/show_bug.cgi?id=98797#c94

No.  The ELD does not come directly from the display.  The ELD is built from
the EDID by the drm_edid_to_eld routine.  This routine explicitly clears the
conn_type field (effectively leaving the conn_type set as "HDMI", regardless of
the monitor).  

The graphics driver is supposed to fill in the conn_type field.  At least in my
setup, that is done correctly by the intel_audio_codec_enable routine.  (It
sets conn_type of DP, as it is talking to the LSPCON.)

The problem is, after intel_audio_codec_enable sets the conn_type field, the
entire ELD is overwritten by subsequent invocations of drm_edid_to_eld.  It is
this overwritten version of ELD that makes its way to the audio driver.

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