RE: [lkp] [ALSA] ca53fbf3a6: WARNING: CPU: 0 PID: 151 at sound/hda/hdac_i915.c:129 pin2port+0x2a/0x40 [snd_hda_core]()

[Lin, Mengdong]

> -----Original Message-----
> From: Takashi Iwai [mailto:tiwai@xxxxxxx]
> Sent: Monday, March 14, 2016 9:03 PM
> To: Yang, Libin
> Cc: kernel test robot; lkp@xxxxxx; LKML; Wu, Fengguang; Lin, Mengdong
> Subject: Re: [lkp] [ALSA] ca53fbf3a6: WARNING: CPU: 0 PID: 151 at
> sound/hda/hdac_i915.c:129 pin2port+0x2a/0x40 [snd_hda_core]()
> 
> On Mon, 14 Mar 2016 13:02:39 +0100,
> Yang, Libin wrote:
> >
> > Hi Takashi,
> >
> > > -----Original Message-----
> > > From: Takashi Iwai [mailto:tiwai@xxxxxxx]
> > > Sent: Monday, March 14, 2016 3:23 PM
> > > To: kernel test robot
> > > Cc: lkp@xxxxxx; LKML; Wu, Fengguang; Yang, Libin; Lin, Mengdong
> > > Subject: Re: [lkp] [ALSA] ca53fbf3a6: WARNING: CPU: 0 PID: 151 at
> > > sound/hda/hdac_i915.c:129 pin2port+0x2a/0x40 [snd_hda_core]()
> > >
> > > On Mon, 14 Mar 2016 01:50:45 +0100,
> > > kernel test robot wrote:
> > > >
> > > > FYI, we noticed the below changes on
> > > >
> > > > https://github.com/0day-ci/linux
> > > > Takashi-Iwai/ALSA-hda-Add-a-sanity-
> > > check-of-pin-port-mapping-on-i915-HDMI-DP/20160310-225740
> > > > commit ca53fbf3a609b6831222078af9ddbecbf76fddce ("ALSA: hda -
> > > Add a sanity check of pin / port mapping on i915 HDMI/DP")
> > > >
> > > >
> > > > [   14.546058] snd_hda_intel 0000:00:1b.0: bound 0000:00:02.0
> (ops
> > > i915_audio_component_bind_ops [i915])
> > > > [   14.549740] fbcon: inteldrmfb (fb0) is primary device
> > > > [   14.553691] ------------[ cut here ]------------
> > > > [   14.553707] WARNING: CPU: 0 PID: 151 at
> > > sound/hda/hdac_i915.c:129 pin2port+0x2a/0x40 [snd_hda_core]()
> > >
> > > Does your tree contain the commit
> > >   2f791908a70e95768596f5bb9e6de4f441d7bf13
> > >       drm/i915: Fix bogus dig_port_map[] assignment for pre-HSW ?
> > >
> > > The commit above should cover it even for HSW.
> > >
> > > If it's already included, then it's really a bug, and the warning is
> > > exactly for catching such a bug.  The HD-audio driver expects that
> > > the valid audio ports are only from port B to port D while i915
> > > driver assigns a different one.  I suspect that the current
> > > assumption is too naive and broken for SKL and later in this regard.
> > >
> > > Libin, Mengdong, could you check whether the audio port mapping rule
> > > is still valid?  At least, a wrong port-A mapping could be
> > > reproduced even on a HSW laptop with DP-MST dock when I boot
> without
> > > eDP (e.g. video=eDP-1:d option).
> >
> > We checked with HW before, and the mapping should be right.
> > What's the problem now? I will check with our HW and gfx team.
> 
> One problem I've heard is that port-A is reported from i915 ELD notifier.
> This happens when you disable eDP and use DP-MST on a HSW machine.
> Then port A DDI is also used for the DP-MST, and when it's plugged, it passes
> port=0 to the notifier.

Hi Takashi,

Could you or someone provide the output of intel_audio_dump when the error happens?
This can help us to check the pipe:port connections in GPU from the display register values.

For Haswell and later platforms, port A (DDI A) is only used for eDP, not for DP or HDMI. So I feel the DP-MST dock should not bridge port A to external monitors and so port A should not be reported by the ELD notifier.
Maybe the port mapping has bug since i915 support for DP MST is still ongoing. 

Thanks
Mengdong