[alsa-devel] Bug 48381 - [Regression][Bisected]Sound gets permanently muted a few minutes after booting

[Da Fox]

Hi all,

Since the official bug-tracker at
https://bugtrack.alsa-project.org/alsa-bug/ seems to be down (and
moreover this appears to be a kernel bug), I have filed a bug at the
kernel's bug-tracker last week (
https://bugzilla.kernel.org/show_bug.cgi?id=48381 ). However, it seems
to have gone unnoticed thus-far.

Quick summary of the issue:
After a while of inactivity the sound-card seems to go into a sort of
power-saving mode (you can hear a faint 'pop' from the speakers).
Before the sound would automatically turn back on again as soon as a
program attempted to play sound. However now it seems that after
resuming from the power-saving mode the driver thinks that there is
always a headphone connected, even when it is not. I think this is
what happens because toggling the 'Auto-Mute Mode' (setting it to
'Disabled') in alsamixer allows the speakers to produce sound again.
This is all on a laptop (please see the linked bug report for more
detailed hardware description).

Would a developer please take a look at it? I have bisected the issue
down to a commit made by David Henningsson and/or Takashi Iwai:
---8<---------
80c8bfbe76869bfd6bdf3d260d316e7a32f318c3 is the first bad commit
commit 80c8bfbe76869bfd6bdf3d260d316e7a32f318c3
Author: David Henningsson <david.henningsson at canonical.com>
Date:   Mon Jun 4 09:33:51 2012 +0200

    ALSA: HDA: Create phantom jacks for fixed inputs and outputs

    PulseAudio sometimes have difficulties knowing that there is a
    "Speaker" or "Internal Mic", if they have no individual volume
    controls or selectors. As a result, only e g "Headphone" might
    be created for a laptop, but no "Speaker".
    To help out, create phantom jacks (that are always present,
    at least for now) for "Speaker", "Internal Mic" etc, in case we
    detect them.
    The naming convention is e g "Speaker Phantom Jack".

    In order not to pollute the /dev/input namespace with even more
    devices, these are added to the kcontrols only, not the input devices.

    Signed-off-by: David Henningsson <david.henningsson at canonical.com>
    Signed-off-by: Takashi Iwai <tiwai at suse.de>

:040000 040000 7a954b731bef80cee731763521f64a424a7058a0
7d176b02ebb4553b0b0f97d200f7527cb69c122a M    sound
--->8---------

If any additional information is required please let me know.

Best regards,
  Da Fox