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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.
-With the automatic power-saving, the driver turns off the codec power
-appropriately when no operation is required. When no applications use
-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
-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_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
-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):
- # echo 10 > /sys/modules/snd_ac97_codec/parameters/power_save
-Note that you might hear click noise/pop when changing the power
-state. Also, it often takes certain time to wake up from the
-power-down to the active state. These are often hardly to fix, so
-don't report extra bug reports unless you have a fix patch ;-)
-For HD-audio interface, there is another module option,
-power_save_controller. This enables/disables the power-save mode of
-the controller side. Setting this on may reduce a bit more power
-consumption, but might result in longer wake-up time and click noise.
-Try to turn it off when you experience such a thing too often.