Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 48e92b48 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: doc: ReSTize powersave document



A simple conversion from a text file.
Put into designs subdirectory, although it's mostly relevant with
HD-audio.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent afb8fd3c
Loading
Loading
Loading
Loading
+1 −0
Original line number Diff line number Diff line
@@ -5,3 +5,4 @@ Designs and Implementations
   :maxdepth: 2

   procfile
   powersave
+9 −7
Original line number Diff line number Diff line
==========================
Notes on Power-Saving Mode
==========================

AC97 and HD-audio drivers have the automatic power-saving mode.
This feature is enabled via Kconfig CONFIG_SND_AC97_POWER_SAVE
and CONFIG_SND_HDA_POWER_SAVE options, respectively.
This feature is enabled via Kconfig ``CONFIG_SND_AC97_POWER_SAVE``
and ``CONFIG_SND_HDA_POWER_SAVE`` options, respectively.

With the automatic power-saving, the driver turns off the codec power
appropriately when no operation is required.  When no applications use
@@ -11,20 +12,21 @@ the device and/or no analog loopback is set, the power disablement is
done fully or partially.  It'll save a certain power consumption, thus
good for laptops (even for desktops).

The time-out for automatic power-off can be specified via power_save
The time-out for automatic power-off can be specified via ``power_save``
module option of snd-ac97-codec and snd-hda-intel modules.  Specify
the time-out value in seconds.  0 means to disable the automatic
power-saving.  The default value of timeout is given via
CONFIG_SND_AC97_POWER_SAVE_DEFAULT and
CONFIG_SND_HDA_POWER_SAVE_DEFAULT Kconfig options.  Setting this to 1
``CONFIG_SND_AC97_POWER_SAVE_DEFAULT`` and
``CONFIG_SND_HDA_POWER_SAVE_DEFAULT`` Kconfig options.  Setting this to 1
(the minimum value) isn't recommended because many applications try to
reopen the device frequently.  10 would be a good choice for normal
operations.

The power_save option is exported as writable.  This means you can
The ``power_save`` option is exported as writable.  This means you can
adjust the value via sysfs on the fly.  For example, to turn on the
automatic power-save mode with 10 seconds, write to
/sys/modules/snd_ac97_codec/parameters/power_save (usually as root):
``/sys/modules/snd_ac97_codec/parameters/power_save`` (usually as root):
::

	# echo 10 > /sys/modules/snd_ac97_codec/parameters/power_save