[alsa-devel] [PATCH 2/2] [RFC] ALSA: hda: hdmi - preserve non-MST PCM routing for Intel platforms

[Kai Vehmanen]

Hi Takashi and Nikhil,

On Mon, 2 Dec 2019, Kai Vehmanen wrote:
> yup, -1 for non-MST, that was just plain wrong in my Friday mail. The 
> problem seems to be pipe id is positive in some non-MST cases (like 
> https://github.com/thesofproject/linux/issues/1536 ), which is very 
> suprising looking at e.g. intel_audio_codec_enable(), but that seems to be 
> happening nevertheless.

ok, got graphics driver log from this case now, and this turns out to be a 
system with an unusual converter setup for HDMI output. I.e. from user 
point of view it's HDMI, but for graphics driver it looks like a DP 
connection (with MST enabled which is not so common but apparently is the 
case). So i915 driver is working as expected and in patch_hdmi we should 
handle it as a normal MST case.

Takashi, considering the commit message is wrong, I think it's better
to revert the "ALSA: hda: hdmi - preserve non-MST PCM routing for Intel 
platforms" patch. Should I send a revert?

It also doesn't fully preseve the old routing as in the case of a single 
DP-MST monitor (with dev_id=1), hdmi_find_pcm_slot() will not pick the 
preferred PCM "per_pin->pin_nid_idx", but will choose "spec->num_nids + 
(per_pin->dev_id - 1)". So seems better to just drop it.

Br, Kai