Re: [snd_hda_intel] snd_hda_intel causes high CPU lockup and system instability if mic disabled in BIOS on Lenovo P50

[Alexander Kappner]

On Wed, 5 Dec 2018, Takashi Iwai wrote:

> On Sat, 01 Dec 2018 20:33:16 +0100,
> Alexander Kappner wrote:
> > On Tue, 27 Nov 2018, Takashi Iwai wrote:
> >
> > > On Tue, 27 Nov 2018 06:34:02 +0100,
> > > Alexander Kappner wrote:
> > > > On Mon, 26 Nov 2018, Takashi Iwai wrote:
> > > >
> > > > > On Mon, 26 Nov 2018 00:17:15 +0100,
> > > > > Alexander Kappner wrote:
> > > > > > My Lenovo P50 laptop has a BIOS option to disable the microphone. When
> > > > > > this option gets chosen, the snd_hda_intel driver causes high CPU load
> > > > > > on a single kworker thread, spinning on "process_unsol_events", and
> > > > > > system
> > > > > > instability. This behavior occurs from the time that the snd_hda_intel
> > > > > > module is loaded, irrespective of whether anything is attempting to access
> > > > > > the mic. The sound output still works.
> > > > > >
> > > > > > When in this state, the module cannot be removed cleanly; attempting to
> > > > > > remove it (even without rmmod -f) triggers an oops.
> > > > > >
> > > > > > I have attached two exemplary dmesg outputs. Strangely enough, the exact
> > > > > > location of the oops varies, but further up the call chain, I always see
> > > > > > process_unsol_events.
> > > > > >
> > > > > > When the mic is not disabled in the BIOS, the module works stable,
> > > > > > regardless whether or not the mic is muted in ALSA.
> > > > > >
> > > > > > I wasn't able to pinpoint the root cause. Any pointers on where to
> > > > > > start? Much appreciated.
> > > > >
> > > > > Could you load snd-hda-intel driver with probe_only=1 option, and give
> > > > > alsa-info.sh output (run it with --no-upload option)?  This should
> > > > > leave only the codec probing without configuring, so we can see the
> > > > > codec widget contents and check the emulator.
> > > > >
> > > > >
> > > > > thanks,
> > > > >
> > > > > Takashi
> > > >
> > > > Hi Takashi,
> > > >
> > > > thank you for looking into this. Please see quoted below the output of
> > > > alsa-info.sh (after "modprobe snd_hda_intel probe_only=1").
> > >
> > > This is the state where BIOS disabled the mic, right?
> > > It seems that BIOS doesn't change the pin configuration.  The pin NID
> > > 0x18 and 0x19 still show up as the mic jack and dock mic jack, as well
> > > as the built-in mic on NID 0x12.  And I couldn't see anything wrong in
> > > the emulator with this input.
> > >
> > > When BIOS disables the mic, how is supposed?  Does it disable all
> > > mics, including built-in one?
> > >
> > > Could you check alsa-info.sh outputs on both BIOS mic disable and
> > > enabled (but keep probe_only=1 option in both cases)?
> > >
> > > Also alsa-info.sh outputs on both cases without probe_only=1 would be
> > > helpful, too.
> > >
> > >
> > > thanks,
> > >
> > > Takashi
> > Hi Takashi,
> >
> > as requestd, please see attached four files, reflecting each
> > combination of probe_only and mic enabled/disabled. To answer your
> > question -- yes, the initial file I had sent reflected the mic
> > disabled state.
> >
> > The BIOS option definitely disables the internal microphone. I could
> > not test whether it would also disable other microphones
> > (e.g. externally connected) since I do not have an external mic, but I
> > will find out.
>
> Hrm, that's strange.  The mic_enabled_default.txt shows "Mic Jack"
> false while the mic_disabled_default.txt shows "Mic Jack" true.
> It sounds like other way round.  Could you confirm this behavior?
>
> In anyway, there seems no difference in the pin configs or such
> between BIOS mic enable/disable.  So this shouldn't be the cause.
>
> And I noticed that you're testing 4.19-rc4.  Could you test with 4.19
> final or 4.19.y stable, at least?
>
>
> thanks,
>
> Takashi
Hi Takashi,

I have been trying to reproduce 
this issue with the more recent 4.20-rc6 kernel, and it has not 
reoccurred. As such, I tentatively consider this issue resolved. Thank you 
for your help.

Best regards
Alexander