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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

Documentation/sound/designs/index.rst

+1 −0
Original line number Diff line number Diff line
@@ -5,3 +5,4 @@ Designs and Implementations 
   :maxdepth: 2



   procfile

   powersave

Documentation/sound/alsa/powersave.txt→Documentation/sound/designs/powersave.rst

+9 −7
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==========================

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