Difference between revisions of "How to make ACPI work"

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===general===
+
==General==
−
First of all you'll have to enable ACPI support in your kernel (if your distro doesn't already have an ACPI enabled kernel).
+
First, simply try using the power management features of Linux on your computer. Tell Linux to suspend (System > Preferences > Power Management in Gnome).  Try closing the lid.   ACPI may already work.
−
To do this open your kernel config, go to <code>Power management options</code>, enable <code>Power Management support</code>, go to <code>ACPI</code> and enable the needed options. You'd most likely want to enable <code>Sleep States</code>, <code>AC Adapter</code>, <code>Battery</code>, <code>Fan</code>, <code>Processor</code> and <code>Thermal Zone</code>. Then recompile your kernel.
 
  
−
If you prefer editing your .config file directly, you should set at least the following variables:
+
===Update BIOS===
 +
ACPI requires a relatively new BIOS version.  In particular, if you get the message,
 +
  ACPI: Could not use ECDT
 +
during startup, you probably need a [[BIOS Upgrade]].  For example, a BIOS upgrade from version 1.02 to 1.10 was all that was needed for ACPI to start working on an A31 2652 running Red Hat Enterprise Linux 5 (CentOS 5).
 +
 
 +
===Kernel configuration===
 +
Many Kernel 2.6 distributions like Red Hat Enterprise Linux 5 (Centos 5) have ACPI built in and ready to go.  If not, you must enable ACPI support in your kernel.
 +
 
 +
To do this open your kernel config and enable ACPI Power Management:
 +
:{{kernelconf|CONFIG_PM|<*>|Power Management support|Power management options|||}}
 +
:{{kernelconf|CONFIG_ACPI|<*>|ACPI Support|Power management options|||}}
 +
 
 +
You'd most likely want to enable the following ACPI options:
 +
:{{kernelconf|CONFIG_SUSPEND|<*>|Suspend to RAM and standby|Power management options|||}}
 +
:{{kernelconf|CONFIG_ACPI_AC|<*>|AC Adapter|ACPI|Power management options||}}
 +
:{{kernelconf|CONFIG_ACPI_BATTERY|<*>|Battery|ACPI|Power management options||}}
 +
:{{kernelconf|CONFIG_ACPI_BUTTON|<*>|Button|ACPI|Power management options||}}
 +
:{{kernelconf|CONFIG_ACPI_FAN|<*>|Fan|ACPI|Power management options||}}
 +
:{{kernelconf|CONFIG_ACPI_PROCESSOR|<*>|Processor|ACPI|Power management options||}}
 +
:{{kernelconf|CONFIG_ACPI_THERMAL|<*>|Thermal Zone|ACPI|Power management options||}}
 +
 
 +
If you prefer editing your {{path|.config}} file directly, you should set at least the following variables:
 
  CONFIG_PM=y
 
  CONFIG_PM=y
−
  CONFIG_ACPI_BOOT=y
+
  CONFIG_ACPI=y
−
CONFIG_ACPI_INTERPRETER=y
 
−
CONFIG_ACPI_SLEEP=y
 
−
CONFIG_ACPI_SLEEP_PROC_FS=y
 
 
  CONFIG_ACPI_AC=y
 
  CONFIG_ACPI_AC=y
 
  CONFIG_ACPI_BATTERY=y
 
  CONFIG_ACPI_BATTERY=y
Line 15: Line 32:
 
  CONFIG_ACPI_PROCESSOR=y
 
  CONFIG_ACPI_PROCESSOR=y
 
  CONFIG_ACPI_THERMAL=y
 
  CONFIG_ACPI_THERMAL=y
−
  CONFIG_ACPI_BUS=y
+
  CONFIG_ACPI_BLACKLIRG_YEAR=0
 
  CONFIG_ACPI_EC=y
 
  CONFIG_ACPI_EC=y
 
  CONFIG_ACPI_POWER=y
 
  CONFIG_ACPI_POWER=y
−
CONFIG_ACPI_PCI=y
 
 
  CONFIG_ACPI_SYSTEM=y
 
  CONFIG_ACPI_SYSTEM=y
  
−
Unfortunately, special drivers for ACPI on ThinkPads were not included with kernels prior 2.6.10. So you'll have to compile one yourself. You have the choice between [[thinkpad-acpi]] and [[ibm-acpi]], with the latter being the recommended one.
+
Then recompile your kernel.  
  
−
Also you'll need to install [[acpid]], if it isn't present on your system. [[acpid]] is a daemon that handles the ACPI events generated by the system. Read [[How to configure acpid]].
+
{{HINT| ACPI SLEEP States option did only show up for me after patching [[Software Suspend 2]] into the kernel. With a vanilla 2.6.17 kernel, one must enable CONFIG_SMP and CONFIG_HOTPLUG_CPU for the option to appear, cf. [http://bugs.debian.org/383059 Debian bug #383059] .
 +
(This should be fixed in 2.6.23, there are new CONFIG_SUSPEND and CONFIG_HIBERNATION config options)}}
 +
 
 +
===Kernel boot parameters===
 +
Many ThinkPads have been hit by a recent (kernel 2.6.16) change to ACPI4Linux that changed the default means of accessing the ACPI Embedded Controller as a way to shake out underlying bugs in the EC access code. If your ThinkPad fails to resume properly (a blinking Sleep light on resume that doesn't go away, or a hang when trying to suspend/standby a second time), adding {{bootparm|ec_intr|0}} to your kernel command line may help.
  
−
In general it is a good idea to read the README included with the ibm-acpi source tarball.
+
===ThinkPad specific ACPI driver===
  
−
===Screen blanking (Standby)===
+
If you are using kernel version 2.6.22 and later, please use the [[thinkpad-acpi]] driver included with the kernel.
−
Make sure you have
 
−
Option "DPMS"
 
−
in the Monitor section of your XF86Config/xorg.conf.
 
  
−
Running {{cmd|xset +dpms}} and then {{cmd|xset dpms force off}} will turn off the backlight on a laptop screen.<br />
+
{{HINT|Generally it is a good idea to read the README included with the driver.}}
  
−
Note that this may not work in combination with {{cmd|echo -n "mem" > /sys/power/state}} because switching to console causes the backlight to come back on before sleeping.
+
===Backlight problems with post-2.6.26 kernels===
  
−
===Suspend to RAM (Sleep)===
+
According to [[http://www.nabble.com/T61-Brightness-keys-with-2.6.26-not-working-(NVIDIA)-td18577619.html this thread]], users with 2.6.26 kernel and higher may experience problems with ThinkPad backlight contols ('''Fn+Home''', '''Fn+End''' on T61). The symptoms are:
−
ACPI Sleep and suspend-to-ram with recent 2.6.x kernels usually works fine. However, the following glitches may or may not occur:
+
* backlight brightness controls do not work;
−
* With a 2.6.9 or 2.6.10 kernel, when resuming from a suspend-to-ram the display might remain black (the system is still rebootable via ctrl-alt-del). This can be fixed by adding <tt>acpi_sleep=s3_bios</tt> to the kernel boot parameters. It seems this problem is solved in 2.6.11-rc1.
+
* Using '''acpi_listen''' command, there is no reaction for '''brightness down''' button, but '''brightenss up''' gives:
−
* When your system is equiped with a Radeon Mobility graphic controller your LCD backlight may not turn off automatically. Use [[radeontool]] to switch off your backlight prior suspend in your script. See also [[T30 ACPI Sleeping]] for specifics about automatically sleeping the T30 (which has a Radeon Mobility) when you close the lid or invoke Fn-F4.
+
  ibm/hotkey HKEY 00000080 00001010
−
* Also, you might want to take note of the [[Problem with high power drain in ACPI sleep]].
 
−
* You may experience problems when using {{cmdroot|echo standby > /sys/power/state}} (machine goes to sleep and wakes up immediately). This can be avoided by using {{cmdroot|echo -n 3 >/proc/acpi/sleep}} to get it to sleep. This can be also happen if hotplug daemon is still running.
 
−
* Problems with the serial port of the port replicator after the wake up from ram have also been experienced.
 
  
−
===Suspend to disk (Hibernate)===
+
The solution is that one needs to enable `CONFIG_VIDEO_OUTPUT_CONTROL`:
−
There are two drivers for this available:
+
Device Drivers  --->
−
* swsusp, which is in the kernel and
+
  Graphics Support  --->
−
* [http://developer.berlios.de/projects/softwaresuspend/ SoftwareSuspend2] which is more feature rich, but not yet in the kernel, so you have to patch it in yourself
+
    <*> Lowlevel video output switch controls
−
Both are reported to work fine as long as you use open-source graphic drivers. A comparison of the features can be found on [http://softwaresuspend.berlios.de/features.html this page].
 
  
−
Just in case you are in doubt...yes, it is safe in both cases to use the same swap partition as active swap and as suspend partition.
+
Subsequently one should enable 'CONFIG_ACPI_VIDEO':
 +
Power Management Options  --->
 +
  [*] ACPI (Advanced Configuration and Power Interface) Support  --->
 +
    <*> Video
  
−
====using swsusp====
+
{{NOTE|Without `CONFIG_VIDEO_OUTPUT_CONTROL` enabled, one will not be able to enable `CONFIG_ACPI_VIDEO` in menuconfig or similar interface as the option will remain hidden}}
−
Software Suspend (swsusp) is included in the 2.6 kernel series. It seems like no patches for 2.4 kernels are available.
 
  
−
To enable it, go to <tt>Power management options</tt> and enable <tt>Power management support</tt> and <tt>Software Suspend</tt> in the kernel config menu. You'll also want to give the swap partition to suspend to in <tt>Default resume partition</tt>.
+
===ACPI S4 hardware signature mismatch===
  
−
In case you prefer to edit your config file directly, you should have the following three entries look like here...
+
Around kernel 2.6.27, a feature was introduced to check the hardware signature on resume from S4 (hibernate). This feature might be broken on some models. Resume will halt and the following error message is shown:
−
CONFIG_PM=y
+
:ACPI: Hardware changed while hibernated, cannot resume!
−
CONFIG_SOFTWARE_SUSPEND=y
+
:Kernel panic - not syncing: ACPI S4 hardware signature mismatch
−
CONFIG_PM_STD_PARTITION="/dev/resume_partition"
+
To fix it, add the following kernel parameter:
−
...where <tt>/dev/resume_partition</tt> needs to be replaced by the swap partition you want to use for suspending. (Use {{cmdroot|fdisk -l /dev/hda}} if unsure.)
+
:acpi_sleep=s4_nohwsig
 +
This problem appeared here on a T42p, but only if the power is unplugged while hibernated, even if the battery is still plugged. Another sympton is, that resume hangs with a dark screen if the acpi_cpufreq module is loaded, even if the power is not unplugged while hibernated. With the above mentioned kernel parameter, both problems go away.
  
−
You can override the default resume partition anytime by giving <tt>resume=/dev/resume_partition</tt> as kernel boot parameter.
+
===ACPI daemon===
−
Also, in case you suspended, but want to boot up normally (without resuming from the saved image - loosing all data that was unsaved at suspend time), you can give the <tt>noresume</tt> kernel boot parameter.
+
Also you'll need to install [[acpid]], if it isn't present on your system. [[acpid]] is a daemon that handles the ACPI events generated by the system. Read [[How to configure acpid]].
  
−
To suspend you can either do a simple {{cmdroot|echo -n 4 > /proc/acpi/sleep}} (recommended) or use the [http://softwaresuspend.berlios.de/old-site/swsusp/sysvinit-2.76-v2-for_swsusp-v5.tar.gz patched SysVInit] and call {{cmdroot|swsusp}} or {{cmdroot|shutdown -z now}}.
+
{{NOTE|For [[acpid]] to work, the ACPI event interface <TT>/proc/acpi/event</TT> must be configured in the kernel (via <TT>CONFIG_ACPI_PROC_EVENT</TT>).  As of kernel 2.6.25, this interface is deprecated.  ACPI events are now distributed through the kernel's input event framework, making [[acpid]] redundant and, ultimately, obsolete. However, userspace utilities have been slow to migrate toward the new interface, and many Linux distributions continue to enable the old interface. Check your kernel configuration, or check to see if <TT>/proc/acpi/event</TT> exists.}}
  
−
Ideally you would do this from a script like <tt>/etc/acpi/actions/hibernate.sh</tt>. It has proven to be a good idea to shutdown the following processes/drivers within the script before you do the actual suspend.
+
==Screen blanking (Standby)==
−
*any running mysql server
+
Make sure you have
−
*the linuxant driver may require stopping in a acpi script as well. {{cmdroot|dldrstop}} does the trick.
+
Option "DPMS"
 +
in the Monitor section of your {{path|/etc/X11/XF86Config}} or {{path|/etc/X11/xorg.conf}}.
  
−
Afterwards you might want to enable them again, as well as run a script that does necessary configurations according to the ac power state.
+
Running {{cmduser|xset +dpms}} and then {{cmduser|xset dpms force off}} will turn off the backlight on a laptop screen.<br />
−
Furthermore, the system clock is not readjusted automatically, so you will probably also want the do that from that script (i.e. by restarting your systemclock bootup script).
 
  
−
If the sound output is silent after resume, these commands might help to get sound to work again without reloading any modules:
+
Note that this may not work in combination with {{cmduser|echo -n "mem" > /sys/power/state}} because switching to console causes the backlight to come back on before sleeping.
  
−
amixer set Master mute >/dev/null 2>&1
+
See also [[How to reduce power consumption#LCD Backlight/Brightness]]
−
amixer set PCM mute >/dev/null 2>&1
 
−
amixer set Master unmute >/dev/null 2>&1
 
−
amixer set PCM unmute >/dev/null 2>&1
 
  
−
Finally you should take note that swsusp does not set the ACPI S4 state. Instead it goes to S5. This means that the machine itself doesn't know that it was suspend rather than shutdown. Hence you can i.e. boot a parallel installed other operating system and resume your linux session later, as long as you don't touch the swap partition the image was saved to.
+
==Suspend to RAM (Sleep)==
 +
ACPI Sleep/suspend-to-ram with recent 2.6.x kernels usually works fine. Have a look at the [[How to configure acpid|acpid configuration HOWTO]]. It includes a specific example for going to sleep on lid close.
  
−
====using SoftwareSuspend2====
+
For Troubleshooting, look at the [[Problems with ACPI suspend-to-ram|Problems with ACPI suspend-to-ram page]].
−
First apply Software Suspend 2 patches from http://softwaresuspend.berlios.de/ if they are not already in your kernel. I am running 2.6.11-rc4-nitro in a Thinkpad T30 2366.
 
  
−
Be sure to also read the http://softwaresuspend.berlios.de/HOWTO.html
+
==Suspend to disk (Hibernate)==
 +
There are two drivers for this available:
 +
* [[swsusp]], which is in the kernel and
 +
* [[TuxOnIce]] which is more feature rich, but not yet in the kernel, so you have to patch it in yourself.
  
−
These are the options for the kernel. You can change the <tt>/dev/hda5</tt> to your swap partition
+
Both are reported to work fine as long as you use open-source graphic drivers. A comparison of the features can be found on [http://softwaresuspend.berlios.de/features.html this page].
  
−
# Software Suspend 2
+
Just in case you are in doubt...yes, it is safe in both cases to use the same swap partition as active swap and as suspend partition.
−
CONFIG_SOFTWARE_SUSPEND2=y
 
−
CONFIG_SOFTWARE_SUSPEND2_BUILTIN=y
 
−
CONFIG_SOFTWARE_SUSPEND_SWAPWRITER=y
 
−
CONFIG_SOFTWARE_SUSPEND_LZF_COMPRESSION=y
 
−
CONFIG_SOFTWARE_SUSPEND_TEXT_MODE=y
 
−
CONFIG_SOFTWARE_SUSPEND_DEFAULT_RESUME2="/dev/hda5"
 
−
# CONFIG_SOFTWARE_SUSPEND_KEEP_IMAGE is not set
 
−
CONFIG_SOFTWARE_SUSPEND_CHECK_RESUME_SAFE=y
 
−
# CONFIG_SOFTWARE_SUSPEND_DEBUG is not set
 
−
# CONFIG_SOFTWARE_SUSPEND_DEVELOPER is not set
 
  
−
Next, compile and install the kernel
+
See the according drivers page for instructions.
  
−
In the meantime, add the following to the kernel parameters <tt>resume2=swap:/dev/hda5</tt>. Again change <tt>/dev/hda5</tt> to your swap partition.
+
== Troubleshooting ==
  
−
Install the hibernation script
+
=== Machine reboots after shutting down ===
  
−
For [[:Category:Gentoo | Gentoo]] users: emerge hibernate-script<br />
+
Try removing ehci_hcd before shutting down, eg, add the following line to rc.local.shutdown
−
For all other users, check the home page for packages (deb, i386 rpm, tgz, and source rpm) from http://softwaresuspend.berlios.de/
 
  
−
Restart using the new kernel and run the script to test it out.
+
rmmod ehci_hcd
−
/usr/sbin/hibernate
 
  
 +
Needed on {{X220}} and {{X230|Reboots after shutting down}}.
  
−
[[Category:570]] [[Category:570E]] [[Category:A20m]] [[Category:A20p]] [[Category:A20m]] [[Category:A20p]] [[Category:A21e]] [[Category:A21m]] [[Category:A21p]] [[Category:A22e]] [[Category:A22m]] [[Category:A22p]] [[Category:G40]] [[Category:G41]] [[Category:R30]] [[Category:R31]] [[Category:R32]] [[Category:R40]] [[Category:R40e]] [[Category:R50]] [[Category:R50p]] [[Category:R51]] [[Category:T20]] [[Category:T21]] [[Category:T22]] [[Category:T23]] [[Category:T30]] [[Category:T40]] [[Category:T40p]] [[Category:T41]] [[Category:T41p]] [[Category:T42]] [[Category:T42p]] [[Category:X20]] [[Category:X21]] [[Category:X22]] [[Category:X23]] [[Category:X24]] [[Category:X30]] [[Category:X31]] [[Category:X40]]
+
==ThinkPads on which it is recommended to use ACPI==
 +
*ThinkPad {{770X}}, {{770Z}}
 +
*ThinkPad {{A20m}}, {{A20p}}, {{A20m}}, {{A20p}}, {{A21e}}, {{A21m}}, {{A21p}}, {{A22e}}, {{A22m}}, {{A22p}}, {{A30}}, {{A30p}}, {{A31}}, {{A31p}}
 +
*ThinkPad {{G40}}, {{G41}}
 +
*ThinkPad {{R30}}, {{R31}}, {{R32}}, {{R40}}, {{R40e}}, {{R50}}, {{R50e}}, {{R50p}}, {{R51}}, {{R52}}, {{R60}}
 +
*ThinkPad {{T22}}, {{T23}}, {{T30}}, {{T40}}, {{T40p}}, {{T41}}, {{T41p}}, {{T42}}, {{T42p}}, {{T43}}, {{T43p}}, {{T61}}
 +
*ThinkPad {{X20}}, {{X21}}, {{X22}}, {{X23}}, {{X24}}, {{X30}}, {{X31}}, {{X32}}, {{X40}}, {{X41}}, {{X41T}}
 +
*ThinkPad {{Z60t}}, {{Z60m}}, {{Z61m}}
 +
*ThinkPad {{X60s}}
 +
*ThinkPad {{TransNote}}
 +
*ThinkPad {{T20}} and {{T21}} have old ACPI implementations, but there have been some reports of using ACPI successfully on these models with Ubuntu and Mandriva in particular. Check the related pages about installing Linux on these models for details.

Latest revision as of 03:24, 28 October 2015

General

First, simply try using the power management features of Linux on your computer. Tell Linux to suspend (System > Preferences > Power Management in Gnome). Try closing the lid. ACPI may already work.

Update BIOS

ACPI requires a relatively new BIOS version. In particular, if you get the message, 

  ACPI: Could not use ECDT

during startup, you probably need a BIOS Upgrade. For example, a BIOS upgrade from version 1.02 to 1.10 was all that was needed for ACPI to start working on an A31 2652 running Red Hat Enterprise Linux 5 (CentOS 5).

Kernel configuration

Many Kernel 2.6 distributions like Red Hat Enterprise Linux 5 (Centos 5) have ACPI built in and ready to go. If not, you must enable ACPI support in your kernel.

To do this open your kernel config and enable ACPI Power Management:

Power management options → <*>Power Management support (CONFIG_PM)
Power management options → <*>ACPI Support (CONFIG_ACPI)

You'd most likely want to enable the following ACPI options:

Power management options → <*>Suspend to RAM and standby (CONFIG_SUSPEND)
Power management options → ACPI → <*>AC Adapter (CONFIG_ACPI_AC)
Power management options → ACPI → <*>Battery (CONFIG_ACPI_BATTERY)
Power management options → ACPI → <*>Button (CONFIG_ACPI_BUTTON)
Power management options → ACPI → <*>Fan (CONFIG_ACPI_FAN)
Power management options → ACPI → <*>Processor (CONFIG_ACPI_PROCESSOR)
Power management options → ACPI → <*>Thermal Zone (CONFIG_ACPI_THERMAL)

If you prefer editing your .config file directly, you should set at least the following variables: 

CONFIG_PM=y
CONFIG_ACPI=y
CONFIG_ACPI_AC=y
CONFIG_ACPI_BATTERY=y
CONFIG_ACPI_BUTTON=y
CONFIG_ACPI_FAN=y
CONFIG_ACPI_PROCESSOR=y
CONFIG_ACPI_THERMAL=y
CONFIG_ACPI_BLACKLIRG_YEAR=0
CONFIG_ACPI_EC=y
CONFIG_ACPI_POWER=y
CONFIG_ACPI_SYSTEM=y

Then recompile your kernel.

Hint:
ACPI SLEEP States option did only show up for me after patching Software Suspend 2 into the kernel. With a vanilla 2.6.17 kernel, one must enable CONFIG_SMP and CONFIG_HOTPLUG_CPU for the option to appear, cf. Debian bug #383059 .

(This should be fixed in 2.6.23, there are new CONFIG_SUSPEND and CONFIG_HIBERNATION config options)

Kernel boot parameters

Many ThinkPads have been hit by a recent (kernel 2.6.16) change to ACPI4Linux that changed the default means of accessing the ACPI Embedded Controller as a way to shake out underlying bugs in the EC access code. If your ThinkPad fails to resume properly (a blinking Sleep light on resume that doesn't go away, or a hang when trying to suspend/standby a second time), adding ec_intr=0 to your kernel command line may help.

ThinkPad specific ACPI driver

If you are using kernel version 2.6.22 and later, please use the thinkpad-acpi driver included with the kernel.

Hint:
Generally it is a good idea to read the README included with the driver.

Backlight problems with post-2.6.26 kernels

According to [this thread], users with 2.6.26 kernel and higher may experience problems with ThinkPad backlight contols (Fn+Home, Fn+End on T61). The symptoms are:

  • backlight brightness controls do not work;
  • Using acpi_listen command, there is no reaction for brightness down button, but brightenss up gives:
 ibm/hotkey HKEY 00000080 00001010

The solution is that one needs to enable `CONFIG_VIDEO_OUTPUT_CONTROL`: 

Device Drivers  --->
  Graphics Support  --->
    <*> Lowlevel video output switch controls

Subsequently one should enable 'CONFIG_ACPI_VIDEO': 

Power Management Options  --->
  [*] ACPI (Advanced Configuration and Power Interface) Support  --->
    <*> Video
NOTE!
Without `CONFIG_VIDEO_OUTPUT_CONTROL` enabled, one will not be able to enable `CONFIG_ACPI_VIDEO` in menuconfig or similar interface as the option will remain hidden

ACPI S4 hardware signature mismatch

Around kernel 2.6.27, a feature was introduced to check the hardware signature on resume from S4 (hibernate). This feature might be broken on some models. Resume will halt and the following error message is shown:

ACPI: Hardware changed while hibernated, cannot resume!
Kernel panic - not syncing: ACPI S4 hardware signature mismatch

To fix it, add the following kernel parameter:

acpi_sleep=s4_nohwsig

This problem appeared here on a T42p, but only if the power is unplugged while hibernated, even if the battery is still plugged. Another sympton is, that resume hangs with a dark screen if the acpi_cpufreq module is loaded, even if the power is not unplugged while hibernated. With the above mentioned kernel parameter, both problems go away.

ACPI daemon

Also you'll need to install acpid, if it isn't present on your system. acpid is a daemon that handles the ACPI events generated by the system. Read How to configure acpid.

NOTE!
For acpid to work, the ACPI event interface /proc/acpi/event must be configured in the kernel (via CONFIG_ACPI_PROC_EVENT). As of kernel 2.6.25, this interface is deprecated. ACPI events are now distributed through the kernel's input event framework, making acpid redundant and, ultimately, obsolete. However, userspace utilities have been slow to migrate toward the new interface, and many Linux distributions continue to enable the old interface. Check your kernel configuration, or check to see if /proc/acpi/event exists.

Screen blanking (Standby)

Make sure you have 

Option "DPMS"

in the Monitor section of your /etc/X11/XF86Config or /etc/X11/xorg.conf.

Running $ xset +dpms and then $ xset dpms force off will turn off the backlight on a laptop screen.

Note that this may not work in combination with $ echo -n "mem" > /sys/power/state because switching to console causes the backlight to come back on before sleeping.

See also How to reduce power consumption#LCD Backlight/Brightness

Suspend to RAM (Sleep)

ACPI Sleep/suspend-to-ram with recent 2.6.x kernels usually works fine. Have a look at the acpid configuration HOWTO. It includes a specific example for going to sleep on lid close.

For Troubleshooting, look at the Problems with ACPI suspend-to-ram page.

Suspend to disk (Hibernate)

There are two drivers for this available:

  • swsusp, which is in the kernel and
  • TuxOnIce which is more feature rich, but not yet in the kernel, so you have to patch it in yourself.

Both are reported to work fine as long as you use open-source graphic drivers. A comparison of the features can be found on this page.

Just in case you are in doubt...yes, it is safe in both cases to use the same swap partition as active swap and as suspend partition.

See the according drivers page for instructions.

Troubleshooting

Machine reboots after shutting down

Try removing ehci_hcd before shutting down, eg, add the following line to rc.local.shutdown 

rmmod ehci_hcd

Needed on X220 and X230.

ThinkPads on which it is recommended to use ACPI

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