threeeye
bc1d038eac
Squashed backup commit (no shallow-clone history issues) of xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2 branch, upstream commit 9eece662e) plus all fixes applied to get everpal_defconfig building clean against a modern (GCC 15.2.0) toolchain -- see the previous commit message on the lineage-23.2 branch (also in this repo history is not available here since this is a squashed snapshot; full incremental history lives in the local DL380 checkout and the upstream GitHub remote). Upstream: https://github.com/xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2)
44 lines
2.0 KiB
ReStructuredText
44 lines
2.0 KiB
ReStructuredText
==========================
|
|
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_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
|
|
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.
|