linux-kernel - Re: [BUG] [REGRESSION] [BISECTED] -rc1 breaks audio over HDMI for i915

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Date:	Fri, 12 Feb 2016 17:16:20 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Martin Kepplinger <martink@...teo.de>
Cc:	david.henningsson@...onical.com, han.lu@...el.com,
	libin.yang@...el.com, treding@...dia.com, perex@...ex.cz,
	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [BUG] [REGRESSION] [BISECTED] -rc1 breaks audio over HDMI for i915

On Fri, 12 Feb 2016 16:54:44 +0100,
Martin Kepplinger wrote:
> 
> Am 2016-02-12 um 14:49 schrieb 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@...top:/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.
> > 
> 
> no error in either of the functions. size is always 0, after boot and
> after HDMI plugin. is that normal?

No, it means that no connection is reported back.  Check the call of
i915_audio_component_get_eld() as mentioned in the above.
Does it return 0?  Also I suppose monitor_present is set to false?
If so, it implies that intel_audio_codec_enable() isn't called.

When the above is true, boot with drm.debug=0x0e, and give the kernel
messages.


Takashi