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ALSA: doc: ReSTize powersave document

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

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2016-11-09 15:54:47 +01:00
parent afb8fd3c72
commit 48e92b488d
2 changed files with 10 additions and 7 deletions
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1
Documentation/sound/designs/index.rst
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@ -5,3 +5,4 @@ Designs and Implementations
:maxdepth: 2 :maxdepth: 2
procfile procfile
powersave

16
Documentation/sound/alsa/powersave.txt → Documentation/sound/designs/powersave.rst
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@ -1,9 +1,10 @@
==========================
Notes on Power-Saving Mode Notes on Power-Saving Mode
========================== ==========================
AC97 and HD-audio drivers have the automatic 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 This feature is enabled via Kconfig ``CONFIG_SND_AC97_POWER_SAVE``
and CONFIG_SND_HDA_POWER_SAVE options, respectively. and ``CONFIG_SND_HDA_POWER_SAVE`` options, respectively.
With the automatic power-saving, the driver turns off the codec power With the automatic power-saving, the driver turns off the codec power
appropriately when no operation is required. When no applications use 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 done fully or partially. It'll save a certain power consumption, thus
good for laptops (even for desktops). 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 module option of snd-ac97-codec and snd-hda-intel modules. Specify
the time-out value in seconds. 0 means to disable the automatic the time-out value in seconds. 0 means to disable the automatic
power-saving. The default value of timeout is given via power-saving. The default value of timeout is given via
CONFIG_SND_AC97_POWER_SAVE_DEFAULT and ``CONFIG_SND_AC97_POWER_SAVE_DEFAULT`` and
CONFIG_SND_HDA_POWER_SAVE_DEFAULT Kconfig options. Setting this to 1 ``CONFIG_SND_HDA_POWER_SAVE_DEFAULT`` Kconfig options. Setting this to 1
(the minimum value) isn't recommended because many applications try to (the minimum value) isn't recommended because many applications try to
reopen the device frequently. 10 would be a good choice for normal reopen the device frequently. 10 would be a good choice for normal
operations. 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 adjust the value via sysfs on the fly. For example, to turn on the
automatic power-save mode with 10 seconds, write to 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 # echo 10 > /sys/modules/snd_ac97_codec/parameters/power_save