[PATCH 0/2] Fix beep notifications by Thinkpad's ACPI firmware

[Jarosław Janik <jaroslaw.janik@xxxxxxxxx>]

In Comment 17 of the following bug report:
https://bugzilla.suse.com/show_bug.cgi?id=1228269
user tigerlily had complained about "audible blip on shutdown" on a
Thinkpad laptop, that led to a commit 4f61c8fe3520 ("ALSA: hda/conexant:
Mute speakers at suspend / shutdown"), which mutes speakers on system
shutdown or whenever HDA controller is suspended by PM. The
aforementioned "blip" is a feature, not a bug however - Thinkpad's ACPI
firmware uses short beeps / beep sequences as notifications in response
to various events (enter/leave suspend or hibernation, AC power
connect/disconnect, low battery, etc.); these can also be triggered by
writing to /proc/acpi/ibm/beep, see details here:
https://www.kernel.org/doc/html/v5.4/admin-guide/laptops/thinkpad-acpi.html#acpi-sounds-proc-acpi-ibm-beep
The firmware doesn't touch any mixer, so depending on current mixer
settings these beeps can be loud, silent or even muted completely,
whatever has been set by the user.

The patch in question interferes this badly:
- suspend/hibernate/shutdown related events are muted altogether because
  HDA controller is in suspend mode when they occur (or snd_hda_intel
  module has been closed in the event of system shutdown)
- other events work "randomly", e.g. you can hear AC plug/unplug beep
  if something is playing audio at the moment, otherwise the HDA
  controller is likely in suspend mode, so you can't hear anything
  (unless you disabled PM in snd_hda_intel module).

That said - let's revert this; this is what 1st commit does, the 2nd
commit is somewhat optional - it removes helpers introduced to implement
this muting, as they are no longer used.

PS. Don't forget to have this backported to LTS kernels, please.

Jarosław Janik (2):
  Revert "ALSA: hda/conexant: Mute speakers at suspend / shutdown"
  Revert "ALSA: hda/generic: Add a helper to mute speakers at
    suspend/shutdown"

 sound/pci/hda/hda_generic.c    | 63 ----------------------------------
 sound/pci/hda/hda_generic.h    |  1 -
 sound/pci/hda/patch_conexant.c |  2 --
 3 files changed, 66 deletions(-)

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2.39.5