[alsa-devel] [BUG] [REGRESSION] [BISECTED] -rc1 breaks audio over HDMI for i915

[Takashi Iwai]

On Fri, 12 Feb 2016 14:09:36 +0100,
Martin Kepplinger wrote:
> 
> Am 2016-02-11 um 10:06 schrieb Takashi Iwai:
> > On Wed, 10 Feb 2016 18:21:11 +0100,
> > Martin Kepplinger wrote:
> >>
> >> Am 2016-02-09 um 12:44 schrieb Takashi Iwai:
> >>> On Tue, 09 Feb 2016 07:34:48 +0100,
> >>> Martin Kepplinger wrote:
> >>>>
> >>>> The following change:
> >>>>
> >>>> 788d441 ALSA: hda - Use component ops for i915 HDMI/DP audio jack handling
> >>>>
> >>>> breaks audio over HDMI on my snd_hda_intel laptop. It is the first bad
> >>>> commit.
> >>>>
> >>>> This was merged for -rc1 and isn't fixed until now, so I got nervous.
> >>>> There are
> >>>> no errors in the log that stand out. I'm no sound or alsa developer, and
> >>>> just reverting it isn't easy since there is stuff depending on this.
> >>>>
> >>>> I'm happy to test possible fixes and hope v4.5 not to ship with such a big
> >>>> regression ;)
> >>>
> >>> Could you give a bit more detail about your hardware?  At best, give
> >>> alsa-info.sh output (run with --no-upload option).  Also, give the
> >>> output of dmesg, too.
> >>>
> >>> In addition, what shows /proc/asound/card*/eld#*.* files?  Does any of
> >>> it show the proper connection state and ELD?
> >>
> >> alsa-info and dmesg are appended, and
> >>
> >> root at laptop:/home/martin/dev# cat /proc/asound/card*/eld#*
> >> monitor_present		0
> >> eld_valid		0
> > 
> > OK, then could you put some debug print in intel_pin_eld_notify() in
> > sound/pci/hda/patch_hdmi.c?  This is the callback to be called by i915
> > driver at enabling / disabling HDMI/DP audio.
> 
> intel_pin_eld_notify() is called during HDMI plugin with
> 
> audio_ptr: ffff880242ea8800, port 1
> 
> and doesn't return early.

OK, so it was processed but the ELD wasn't updated by some reason.

> > (Also, to be sure, check whether snd_hdac_i915_register_notifier() in
> >  sound/hda/hda_i915.c is called, too.)
> 
> snd_hdac_i915_register_notifier() is called during boot.
> 
> > 
> > If intel_pin_eld_notify() is registered but never called, it implies
> > something wrong in i915 driver side.  If it gets called, we need to
> > track down: what port value was passed there, and how
> > hdmi_present_sense() and sync_eld_via_acomp() behave there.
> 
> I'll try to look at said path, if you have no other idea in the meantime.

Put some debug prints in sync_eld_via_acomp(), e.g. check whether
snd_hdac_acomp_get_eld() returns an error or snd_hdmi_parse_eld()
returns an error.  If you got an error, track down more deeply.

For example, the former function is defined in sound/hda/hdac_i915.c,
and it calls the function i915_audio_component_get_eld() in
drivers/gpu/drm/i915/intel_audio.c.  You can follow what returns an
error.

Similarly, the latter function is defined in sound/pci/hda/hda_eld.c.
Usually you see a kernel message for parse errors, so I guess this
isn't the case, though.


Takashi