How to enable audio codec power saving - Revision history

Hmh: How to enable AC97 power saving moved to How to enable audio codec power saving: The page now covers non-AC97 codecs as well

2008-01-27T19:36:22Z

How to enable AC97 power saving moved to How to enable audio codec power saving: The page now covers non-AC97 codecs as well

Hmh: clean up page, fleshen up introductory text

2008-01-27T19:35:13Z

clean up page, fleshen up introductory text

Hmh: Fix layout: re-add subsection header, and use audio codec bus type as subsubsections

2008-01-27T19:29:59Z

Fix layout: re-add subsection header, and use audio codec bus type as subsubsections

Kevmitch: /* On-demand power control */

2008-01-27T07:39:09Z

‎On-demand power control

Hmh: /* On-demand power control */ Fix units. A thinkpad simply can't draw >100W unless it is shorted

2007-03-24T20:57:33Z

‎On-demand power control: Fix units. A thinkpad simply can't draw >100W unless it is shorted

Hmh: /* On-demand power control */ reword it to be impersonal

2007-03-24T20:55:32Z

‎On-demand power control: reword it to be impersonal

Nischu: /* On-demand power control */

2007-03-24T19:45:30Z

‎On-demand power control

Ungoliant: /* On-demand power control , confirms that X31 is supported with kernel version 2.6.20*/

2007-02-21T00:44:44Z

‎On-demand power control , confirms that X31 is supported with kernel version 2.6.20

Hmh: /* On-demand power control */ add link to 2.6.19-rc3 ac97 powersave fix

2006-10-24T14:46:08Z

‎On-demand power control: add link to 2.6.19-rc3 ac97 powersave fix

Thinker: /* On-demand power control */ in 2.6.19 git

2006-10-07T20:41:00Z

‎On-demand power control: in 2.6.19 git

@@ Line 1: / Line 1: @@
-The AC97 sound device (e.g., AD1981B) requires a noticable amount of power (0.3W on {{T43}}). This power can be saved when the device is not in use.
+=How to enable audio codec power saving=
 ==Disabling the device==
-Disable the sound device by unloading modules or {{cmdroot|echo -n 3 >  /sys/class/sound/controlC0/device/power/state}} (replace 3 by 0 to enable again).
+Disable the entire sound device by unloading modules or, on older kernels, by {{cmdroot|echo -n 3 >  /sys/class/sound/controlC0/device/power/state}} (replace 3 by 0 to enable again).
 ==On-demand power control==
 ===AC97 audio subsystem===
 There's an [http://www.kernel.org/git/?p=linux/kernel/git/perex/alsa.git;a=commitdiff_plain;h=6dbe662874ba08585eaf732d126762c25ac8e3f7;hp=2b29b13c5794f648cd5e839796496704d787f5a6 experimental patch from 2.6.19-rc2], [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff_plain;h=da43deb116c0cea9ca2174f2ac64985c4d53077e;hp=dbedca39fe30db87b6401e4396f959c63d90082e that was later corrected in 2.6.19-rc3], which enables the support of aggressive AC97 power-saving mode in the Linux [[ALSA]] drivers.  In this mode, the AC97 powerdown register bits are dynamically controlled at each open/close of PCM streams. To allow powering off the analog mixer, make sure all analog inputs (Line, Microphone, CD, etc.) are muted.
@@ Line 15: / Line 20: @@
 There are reports that on-demand power control can save 0.2W.  Make sure the microphone is muted, though, or its channel won't be turned off.
 ===HDA audio subsystem===
 If you have one of the newer Intel chips, there is an equivalent feature as of kernel 2.6.24, you can select the CONFIG_SND_HDA_POWER_SAVE option and set CONFIG_SND_HDA_POWER_SAVE_DEFAULT to the number of seconds after which you want the device to time out.

@@ Line 4: / Line 4: @@
 Disable the sound device by unloading modules or {{cmdroot|echo -n 3 >  /sys/class/sound/controlC0/device/power/state}} (replace 3 by 0 to enable again).
-==hda_ac97==
+==On-demand power control==
 There's an [http://www.kernel.org/git/?p=linux/kernel/git/perex/alsa.git;a=commitdiff_plain;h=6dbe662874ba08585eaf732d126762c25ac8e3f7;hp=2b29b13c5794f648cd5e839796496704d787f5a6 experimental patch from 2.6.19-rc2], [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff_plain;h=da43deb116c0cea9ca2174f2ac64985c4d53077e;hp=dbedca39fe30db87b6401e4396f959c63d90082e that was later corrected in 2.6.19-rc3], which enables the support of aggressive AC97 power-saving mode in the Linux [[ALSA]] drivers.  In this mode, the AC97 powerdown register bits are dynamically controlled at each open/close of PCM streams. To allow powering off the analog mixer, make sure all analog inputs (Line, Microphone, CD, etc.) are muted.
@@ Line 14: / Line 15: @@
 There are reports that on-demand power control can save 0.2W.  Make sure the microphone is muted, though, or its channel won't be turned off.
-==hda_intel==
+===HDA audio subsystem===
-If you have one of the newer intel chips, there is an equivalent feature as of kernel 2.6.24, you can select the CONFIG_SND_HDA_POWER_SAVE option and set CONFIG_SND_HDA_POWER_SAVE_DEFAULT to the number of seconds after which you want the device to time out.
+If you have one of the newer Intel chips, there is an equivalent feature as of kernel 2.6.24, you can select the CONFIG_SND_HDA_POWER_SAVE option and set CONFIG_SND_HDA_POWER_SAVE_DEFAULT to the number of seconds after which you want the device to time out.
 You can also control this on the fly via sysfs:

@@ Line 4: / Line 4: @@
 Disable the sound device by unloading modules or {{cmdroot|echo -n 3 >  /sys/class/sound/controlC0/device/power/state}} (replace 3 by 0 to enable again).
-==On-demand power control==
+==hda_ac97==
 There's an [http://www.kernel.org/git/?p=linux/kernel/git/perex/alsa.git;a=commitdiff_plain;h=6dbe662874ba08585eaf732d126762c25ac8e3f7;hp=2b29b13c5794f648cd5e839796496704d787f5a6 experimental patch from 2.6.19-rc2], [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff_plain;h=da43deb116c0cea9ca2174f2ac64985c4d53077e;hp=dbedca39fe30db87b6401e4396f959c63d90082e that was later corrected in 2.6.19-rc3], which enables the support of aggressive AC97 power-saving mode in the Linux [[ALSA]] drivers.  In this mode, the AC97 powerdown register bits are dynamically controlled at each open/close of PCM streams. To allow powering off the analog mixer, make sure all analog inputs (Line, Microphone, CD, etc.) are muted.
@@ Line 14: / Line 14: @@
 There are reports that on-demand power control can save 0.2W.  Make sure the microphone is muted, though, or its channel won't be turned off.

← Older revision		Revision as of 20:57, 24 March 2007
Line 13:		Line 13:
	You may hear a faint click each time the device is powered up (at start of playback) and each time the device is powered down (2 seconds after playback ends).		You may hear a faint click each time the device is powered up (at start of playback) and each time the device is powered down (2 seconds after playback ends).

−	There are reports that on-demand power control can save 2W. Make sure the microphone is muted, though, or its channel won't be turned off.	+	There are reports that on-demand power control can save 0.2W. Make sure the microphone is muted, though, or its channel won't be turned off.

← Older revision		Revision as of 20:55, 24 March 2007
Line 13:		Line 13:
	You may hear a faint click each time the device is powered up (at start of playback) and each time the device is powered down (2 seconds after playback ends).		You may hear a faint click each time the device is powered up (at start of playback) and each time the device is powered down (2 seconds after playback ends).

−	~~My machine consumes about 119 watts~~. ~~After having enabled this power_save mode it consumes 117 watts if I don~~'t ~~play anything. Consider that your microphone has to~~ be ~~muted~~.	+	There are reports that on-demand power control can save 2W. Make sure the microphone is muted, though, or its channel won't be turned off.

← Older revision	Revision as of 19:36, 27 January 2008
(No difference)

← Older revision		Revision as of 19:45, 24 March 2007
Line 12:		Line 12:

	You may hear a faint click each time the device is powered up (at start of playback) and each time the device is powered down (2 seconds after playback ends).		You may hear a faint click each time the device is powered up (at start of playback) and each time the device is powered down (2 seconds after playback ends).
		+
		+	My machine consumes about 119 watts. After having enabled this power_save mode it consumes 117 watts if I don't play anything. Consider that your microphone has to be muted.

@@ Line 6: / Line 6: @@
 ==On-demand power control==
 There's an [http://www.kernel.org/git/?p=linux/kernel/git/perex/alsa.git;a=commitdiff_plain;h=6dbe662874ba08585eaf732d126762c25ac8e3f7;hp=2b29b13c5794f648cd5e839796496704d787f5a6 experimental patch from 2.6.19-rc2], [http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff_plain;h=da43deb116c0cea9ca2174f2ac64985c4d53077e;hp=dbedca39fe30db87b6401e4396f959c63d90082e that was later corrected in 2.6.19-rc3], which enables the support of aggressive AC97 power-saving mode in the Linux [[ALSA]] drivers.  In this mode, the AC97 powerdown register bits are dynamically controlled at each open/close of PCM streams. To allow powering off the analog mixer, make sure all analog inputs (Line, Microphone, CD, etc.) are muted.
 The mode is disabled by default, and activated via <tt>power_save=1</tt> option for <tt>snd-ac97-codec</tt> driver (at run time, use {{cmdroot|echo Y > /sys/module/snd_ac97_codec/parameters/power_save}}).
 You may hear a faint click each time the device is powered up (at start of playback) and each time the device is powered down (2 seconds after playback ends).