Difference between revisions of "Lenovo ThinkPad T420"

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[[Category:Lenovo]]
 
[[Category:Lenovo]]
−
{{i18n|Lenovo ThinkPad T420}}
+
[[zh-CN:Lenovo ThinkPad T420]]
−
{{Stub}}
+
 
This article covers the installation and configuration of Arch Linux on a Lenovo T420 laptop.
 
This article covers the installation and configuration of Arch Linux on a Lenovo T420 laptop.
  
−
==Installation==
+
== Installation ==
 +
 
 
This laptop supports [[Unified_Extensible_Firmware_Interface|UEFI]] as well as the traditional BIOS.
 
This laptop supports [[Unified_Extensible_Firmware_Interface|UEFI]] as well as the traditional BIOS.
  
 
There are no issues with installing Arch Linux with the latest [https://www.archlinux.org/download/ Archiso].
 
There are no issues with installing Arch Linux with the latest [https://www.archlinux.org/download/ Archiso].
  
−
The rest of the installation process can be followed with the [[Official_Arch_Linux_Install_Guide|official install guide]].
+
The rest of the installation process can be followed with the [[Installation guide]].
  
−
==Hardware==
+
== Hardware ==
−
All hardware not listed below works out-of-the-box.
+
  
−
===Webcam===
+
All hardware works out of the box except the following:
−
The integrated [[Webcam_Setup|webcam]] uses the {{ic|uvcvideo}} module which should load automatically. If not, add it to the {{ic|MODULES}} array in {{ic|/etc/[[rc.conf]]}}.
+
 
 +
=== Fingerprint reader ===
  
−
===Fingerprint reader===
 
 
Fingerprint reader works great with fprint and PAM (installation of fingerprint-gui recommended).
 
Fingerprint reader works great with fprint and PAM (installation of fingerprint-gui recommended).
  
 
See [[Fprint#Setup_fingerprint-gui]] for more information.
 
See [[Fprint#Setup_fingerprint-gui]] for more information.
  
−
===Untested===
+
=== Some Media keys ===
−
* eSATA
+
 
 +
* See [[#Media Keys|Media Keys]]
 +
 
 +
=== Untested ===
 +
 
 
* Firewire
 
* Firewire
  
 
==Laptop Settings==
 
==Laptop Settings==
 +
 
===ACPI===
 
===ACPI===
 +
 
[[ACPI_modules|ACPI]] is well supported here. No obvious troubleshoots.
 
[[ACPI_modules|ACPI]] is well supported here. No obvious troubleshoots.
  
 
=== Tp_smapi ===
 
=== Tp_smapi ===
 +
 
Unfortunately, [[Tp_smapi|tp_smapi]] is only partially supported on the Thinkpad T420. A number of features work since version 0.41. For example, the hard drive protection mechanism [[HDAPS]] now works well. See the linked wiki entry.
 
Unfortunately, [[Tp_smapi|tp_smapi]] is only partially supported on the Thinkpad T420. A number of features work since version 0.41. For example, the hard drive protection mechanism [[HDAPS]] now works well. See the linked wiki entry.
  
−
Some features like setting the starting threshold for charging the battery do not yet work. To control the battery charging thresholds, install the Perl script {{AUR|tpacpi-bat}} from the [[Arch User Repository|AUR]].
+
Some features like setting the starting threshold for charging the battery do not yet work. To control the battery charging thresholds, install the Perl script {{AUR|tpacpi-bat}} from the [[AUR]].
  
 
Insert the {{ic|acpi_call}} kernel module by running
 
Insert the {{ic|acpi_call}} kernel module by running
 
  modprobe acpi_call
 
  modprobe acpi_call
−
or by adding it to the {{ic|MODULES}} array in {{ic|/etc/[[rc.conf]]}}.
 
  
 
Manually set the thresholds by calling
 
Manually set the thresholds by calling
 
  perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v startChargeThreshold 0 40
 
  perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v startChargeThreshold 0 40
 
  perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v stopChargeThreshold 0 80
 
  perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v stopChargeThreshold 0 80
−
The example values 40 and 80 given here are in percent of the full battery capacity. Adjust them to your own needs. You may also want to add these lines to {{ic|/etc/rc.local}} to set them at startup. While these values should be permanent, they will be reset any time the battery is removed.
+
The example values 40 and 80 given here represent the percentage of full battery capacity remaining. Adjust them to your own needs. You may also want to write a simple {{ic|set-battery.service}} and enable it to set them at startup. While these values should be permanent, they will be reset any time the battery is removed.
 +
 
 +
[Unit]
 +
Description=Set battery capacity
 +
 +
[Service]
 +
Type=oneshot
 +
ExecStart=/usr/bin/perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v stopChargeThreshold 0 80
 +
ExecStart=/usr/bin/perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v startChargeThreshold 0 40
 +
 +
[Install]
 +
WantedBy=multi-user.target
 +
  
 
Also, if you are dual booting with Windows, you can still control the battery charging thresholds with Lenovo's Power Manager which communicates directly to the battery controller.
 
Also, if you are dual booting with Windows, you can still control the battery charging thresholds with Lenovo's Power Manager which communicates directly to the battery controller.
  
−
=== CPU Frequency Scaling ===
+
When using systemd, you may want to blacklist the tp_smapi module if your systemd-modules-load.service fails, as new ThinkPads handle everything over acpi.
 +
 
 +
=== CPU frequency scaling ===
 +
 
 
[[CPU Frequency Scaling|CPU frequency scaling]] is fully supported with all of the available processor models with this laptop.
 
[[CPU Frequency Scaling|CPU frequency scaling]] is fully supported with all of the available processor models with this laptop.
  
 
=== Fans ===
 
=== Fans ===
  
−
The thinkpad_acpi kernel module needs to be configured so user space programs can control the fan speed.
+
Install {{AUR|thinkfan}} from the AUR. It will automatically create the necessary acpi configuration file in "/usr/lib/modprobe.d/thinkpad_acpi.conf".
  
−
{{hc|/etc/modprobe.d/modprobe.conf|2=options thinkpad_acpi fan_control=1}}
+
Copy the example sensor settings file from "/usr/share/doc/thinkfan/examples/thinkfan.conf.simple" to "/etc/thinkfan.conf".
 +
{{bc|sudo cp /usr/share/doc/thinkfan/examples/thinkfan.conf.simple /etc/thinkfan.conf}}
  
−
The [https://aur.archlinux.org/packages.php?ID=24359 thinkfan] configuration file also needs to know how to set the fan speed. Replace the default sensor settings with the following.
+
Aftwards replace the default sensor in the settings file "/etc/thinkfan.conf" with the following.
 +
{{hc|sudo nano /etc/thinkfan.conf|sensor /sys/devices/virtual/thermal/thermal_zone0/temp}}
  
−
{{hc|/etc/thinkfan.conf|sensor /sys/devices/virtual/thermal/thermal_zone0/temp}}
+
In the same configuration file replace the default fan level settings with your needs (the last lines of the file). Usefull values are
 +
{{bc|(0, 0, 42)
 +
(1, 40, 47)
 +
(2, 45, 52)
 +
(3, 50, 57)
 +
(4, 55, 62)
 +
(5, 60, 67)
 +
(6, 65, 72)
 +
(7, 70, 77)
 +
(127, 75, 32767)}}
  
−
You can add or remove services by editing the {{ic|DAEMONS}} array in your /etc/[[rc.conf]] file. It will initially look something like this:
+
Finally enable [[systemd]] [[daemon]] '''thinkfan'''.
−
DAEMONS=(...@thinkfan...)
+
{{bc|sudo systemctl enable thinkfan}}
  
 
=== Laptop Mode Tools ===
 
=== Laptop Mode Tools ===
 +
 
No significant issues were found using [[Laptop Mode Tools]].
 
No significant issues were found using [[Laptop Mode Tools]].
  
−
Posible bug with [[Lenovo_ThinkPad_T420#Shutdown on Battery]]
+
Possible bug with [[#Shutdown on Battery]]
 +
 
 +
{{AUR|tlp}} From the [[AUR]] is an alternative tool that can replace {{Pkg|laptop-mode-tools}}.
  
−
=== PM-Utils ===
+
=== Synaptics ===
−
Suspending and hibernating with [[Pm-utils|pm-utils]] works as intended.
+
  
−
===Synaptics===
 
 
TouchPad and TrackPoint do work out of the box, but the TouchPad is way too sensitive (i.e. fast) to be usable, since it is recognized as a mouse. To fix this, [[pacman|install]] the {{Pkg|xf86-input-synaptics}} package and add the following two files to your {{ic|/etc/X11/xorg.conf.d/}} directory:
 
TouchPad and TrackPoint do work out of the box, but the TouchPad is way too sensitive (i.e. fast) to be usable, since it is recognized as a mouse. To fix this, [[pacman|install]] the {{Pkg|xf86-input-synaptics}} package and add the following two files to your {{ic|/etc/X11/xorg.conf.d/}} directory:
  
Line 99: Line 131:
 
</nowiki>}}
 
</nowiki>}}
  
−
Adjust to your own needs. Read [[Touchpad_Synaptics]] for more information.
+
Adjust to your own needs. Read [[Touchpad Synaptics]] for more information.
  
−
To adjust the speed/sensitivity of the TrackPoint add these lines in your {{ic|/etc/rc.local}} script:
+
To adjust the speed/sensitivity of the TrackPoint add these lines in a systemd tmpfile:
  
−
{{hc|/etc/rc.local|<nowiki>
+
{{hc|/etc/tmpfiles.d/local.conf|
−
TPDEV=/sys/devices/platform/i8042/serio1
+
w /sys/devices/platform/i8042/serio1/speed - - - - 180
−
echo -n 180 > $TPDEV/speed
+
w /sys/devices/platform/i8042/serio1/sensitivity - - - - 200
−
echo -n 200 > $TPDEV/sensitivity
+
}}
−
</nowiki>}}
+
  
 
Possible range of values are 1-255.
 
Possible range of values are 1-255.
  
−
===NVIDIA Optimus===
+
=== NVIDIA Optimus ===
 +
 
 
[[Bumblebee|Bumblebee]] works as intended on models with NVIDIA Optimus
 
[[Bumblebee|Bumblebee]] works as intended on models with NVIDIA Optimus
  
 
=== Optional kernel boot arguments ===
 
=== Optional kernel boot arguments ===
−
Using the following kernel boot parameters [[http://www.phoronix.com/scan.php?page=article&item=intel_i915_power&num=1| drastically reduces battery drain]]:
+
Using the following kernel boot parameters [http://www.phoronix.com/scan.php?page=article&item=intel_i915_power&num=1| reduces battery drain]:
−
{{hc||<nowiki>
+
 
−
pcie_aspm=force
+
{{bc|<nowiki>
 
i915.i915_enable_rc6=1
 
i915.i915_enable_rc6=1
 
i915.i915_enable_fbc=1
 
i915.i915_enable_fbc=1
 
i915.lvds_downclock=1  
 
i915.lvds_downclock=1  
 +
i915.semaphores=1
 
</nowiki>}}
 
</nowiki>}}
  
 +
== Troubleshooting ==
  
−
==Troubleshooting==
 
 
=== Media Keys ===
 
=== Media Keys ===
 +
 
Media keys that work out of the box:
 
Media keys that work out of the box:
 
* Wireless On/Off
 
* Wireless On/Off
Line 132: Line 166:
 
* Mute
 
* Mute
  
 +
Media Keys that Do Not work out of the box:
 +
* [[Lenovo_ThinkPad_T420#Volume_up.2Fdown_not_changing_volume|Volume keys]] (Works out-of-the-box in [[Gnome|Gnome]])
 +
* Microphone mute (Requires a custom kernel patch)
 
You must find a workaround and bind the keys yourself for the rest of them.
 
You must find a workaround and bind the keys yourself for the rest of them.
  
 
=== Rebind Forward and Back keys ===
 
=== Rebind Forward and Back keys ===
 +
 
Keys forward and back (next to cursor keys) can be easily remapped to PageDown/PageUp.
 
Keys forward and back (next to cursor keys) can be easily remapped to PageDown/PageUp.
  
Line 146: Line 184:
 
  xmodmap ~/.Xmodmap
 
  xmodmap ~/.Xmodmap
  
−
You can also re-map AudioPrev ({{Keypress|Fn+Left}}) and AudioNext ({{Keypress|Fn+Right}}) to Home/End:
+
You can also re-map AudioPrev ({{ic|Fn+Left}}) and AudioNext ({{ic|Fn+Right}}) to Home/End:
 
  keysym XF86AudioNext = End
 
  keysym XF86AudioNext = End
 
  keysym XF86AudioPrev = Home
 
  keysym XF86AudioPrev = Home
  
−
{{Note|You have to log out for the changes to take effect.}}
+
{{Note|
 +
* You have to log out for the changes to take effect.
 +
* The keys should work out of the box, at least on [[KDE]].
 +
}}
  
−
{{Note|The keys should work out of the box, at least on [[KDE]].}}
+
=== Turn touchpad on and off ===
  
−
=== Shutdown on Battery ===
+
For some, the ({{ic|Fn+F8}}) key does not switch the touchpad on and off. Here is a simple keybind to add to your {{ic|~/.xbindkeysrc}} for keys to quickly change your touchpad state. For these to take effect, run {{ic|xbindkeysrc}}. This binds {{ic|Fn+F8}} to 'toggle the touchpad on and off'. (Tested in i3wm and xfce4, where normal {{ic|Fn+F8}} does not toggle the touchpad)
−
One user has reported that his T420 was rebooting on shutdown on battery power. This was fixed by disabling the module {{ic|ehci_hcd}}. See [[Kernel_modules#Blacklisting]] for more information.
+
 
 +
# Toggle the Touchpad on|off
 +
"synclient TouchpadOff=$(synclient -l | grep -ce TouchpadOff.*0)"
 +
    m:0x0 + c:199
 +
    XF86TouchpadToggle
 +
 
 +
=== Volume up/down not changing volume ===
 +
 
 +
Another quick keybind for {{ic|~/.xbindkeysrc}} to change the volume (which does not work on some DEs). Again, run {{ic|xbindkeys}} for these to take effect. Taken from [[Xbindkeys]]
 +
 
 +
#increase volume
 +
"amixer set Master playback 1+"
 +
    m:0x0 + c:123
 +
    XF86AudioRaiseVolume
 +
 
 +
#decrase volume
 +
"amixer set Master playback 1-"
 +
    m:0x0 + c:122
 +
    XF86AudioLowerVolume
 +
 
 +
Also, while the mute button works, I rebound it to interface with ALSA.
 +
 
 +
# Toggle mute
 +
"amixer set Master toggle"
 +
    m:0x0 + c:121
 +
    XF86AudioMute
 +
 
 +
=== Shutdown on battery ===
 +
 
 +
Some users have reported that the T420 was rebooting on shutdown on battery power. There have been quite a few attempts to fix this. Three are detailed here.
 +
 
 +
One way is to disable the module {{ic|ehci_hcd}}. See [[Kernel_modules#Blacklisting]] for more information.
  
 
Or try disable Laptop-mode.  
 
Or try disable Laptop-mode.  
−
Add !{{Ic|laptop-mode}} to the {{Ic|DAEMONS}} array in {{ic|/etc/rc.conf}}:
+
Add {{Ic|!laptop-mode}} to the {{Ic|DAEMONS}} array in {{ic|/etc/rc.conf}}:
 
  DAEMONS=(...!laptop-mode...)
 
  DAEMONS=(...!laptop-mode...)
  
−
=== Hang on Reboot ===
+
[https://bbs.archlinux.org/viewtopic.php?pid=1106437#p1106437 This forum post] details another way to have your computer not reboot on shutdown. Turning off the {{ic|laptop-mode}} daemon causes battery life to suffer, so when on the move and in need of a simple way to shutdown, this seems to work better.
 +
 
 +
=== Hang on reboot ===
 +
 
 
This is a problem on many laptops and can be fixed by [[Kernel modules#Blacklisting|blacklisting]] the {{ic|e1000e}} kernel module.
 
This is a problem on many laptops and can be fixed by [[Kernel modules#Blacklisting|blacklisting]] the {{ic|e1000e}} kernel module.
  
−
=== No Backlight Controls ===
+
=== No backlight controls ===
 +
 
 
One user has reported that the brightness controls (fn+home, fn+end) did not work in some desktop environments. This could be fixed by adding the following kernel options:
 
One user has reported that the brightness controls (fn+home, fn+end) did not work in some desktop environments. This could be fixed by adding the following kernel options:
 
  acpi_backlight=vendor acpi_osi=Linux
 
  acpi_backlight=vendor acpi_osi=Linux
 +
 +
Also try to adjust the display in the console and not in X windows.  If you don't have the keybindings correct in X, it will cause a problem.  This can be bypassed if you use a virtual console to adjust the brightness.
  
 
== See also ==
 
== See also ==
 +
 
* [[Lenovo ThinkPad T420s]]
 
* [[Lenovo ThinkPad T420s]]
 +
* [http://sysphere.org/~anrxc/j/articles/thinkpad-t420/index.html Arch Linux on ThinkPad T420i]

Revision as of 18:25, 25 February 2014

This article covers the installation and configuration of Arch Linux on a Lenovo T420 laptop.

Installation

This laptop supports UEFI as well as the traditional BIOS.

There are no issues with installing Arch Linux with the latest Archiso.

The rest of the installation process can be followed with the Installation guide.

Hardware

All hardware works out of the box except the following:

Fingerprint reader

Fingerprint reader works great with fprint and PAM (installation of fingerprint-gui recommended).

See Fprint#Setup_fingerprint-gui for more information.

Some Media keys

Untested

  • Firewire

Laptop Settings

ACPI

ACPI is well supported here. No obvious troubleshoots.

Tp_smapi

Unfortunately, tp_smapi is only partially supported on the Thinkpad T420. A number of features work since version 0.41. For example, the hard drive protection mechanism HDAPS now works well. See the linked wiki entry.

Some features like setting the starting threshold for charging the battery do not yet work. To control the battery charging thresholds, install the Perl script tpacpi-batAUR from the AUR.

Insert the acpi_call kernel module by running 

modprobe acpi_call

Manually set the thresholds by calling 

perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v startChargeThreshold 0 40
perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v stopChargeThreshold 0 80

The example values 40 and 80 given here represent the percentage of full battery capacity remaining. Adjust them to your own needs. You may also want to write a simple set-battery.service and enable it to set them at startup. While these values should be permanent, they will be reset any time the battery is removed. 

[Unit]
Description=Set battery capacity

[Service]
Type=oneshot
ExecStart=/usr/bin/perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v stopChargeThreshold 0 80
ExecStart=/usr/bin/perl /usr/lib/perl5/vendor_perl/tpacpi-bat -v startChargeThreshold 0 40

[Install]
WantedBy=multi-user.target

Also, if you are dual booting with Windows, you can still control the battery charging thresholds with Lenovo's Power Manager which communicates directly to the battery controller.

When using systemd, you may want to blacklist the tp_smapi module if your systemd-modules-load.service fails, as new ThinkPads handle everything over acpi.

CPU frequency scaling

CPU frequency scaling is fully supported with all of the available processor models with this laptop.

Fans

Install thinkfanAUR from the AUR. It will automatically create the necessary acpi configuration file in "/usr/lib/modprobe.d/thinkpad_acpi.conf".

Copy the example sensor settings file from "/usr/share/doc/thinkfan/examples/thinkfan.conf.simple" to "/etc/thinkfan.conf". 

sudo cp /usr/share/doc/thinkfan/examples/thinkfan.conf.simple /etc/thinkfan.conf

Aftwards replace the default sensor in the settings file "/etc/thinkfan.conf" with the following. 

sudo nano /etc/thinkfan.conf
sensor /sys/devices/virtual/thermal/thermal_zone0/temp

In the same configuration file replace the default fan level settings with your needs (the last lines of the file). Usefull values are 

(0,	0,	42)
(1,	40,	47)
(2,	45,	52)
(3,	50,	57)
(4,	55,	62)
(5,	60,	67)
(6,	65,	72)
(7,	70,	77)
(127,	75,	32767)

Finally enable systemd daemon thinkfan. 

sudo systemctl enable thinkfan

Laptop Mode Tools

No significant issues were found using Laptop Mode Tools.

Possible bug with #Shutdown on Battery

tlpAUR From the AUR is an alternative tool that can replace laptop-mode-tools.

Synaptics

TouchPad and TrackPoint do work out of the box, but the TouchPad is way too sensitive (i.e. fast) to be usable, since it is recognized as a mouse. To fix this, install the xf86-input-synaptics package and add the following two files to your /etc/X11/xorg.conf.d/ directory: 

50-thinkpad-trackpoint.conf
 Section "InputClass"
        Identifier      "ThinkPad TrackPoint"
        MatchProduct    "TPPS/2 IBM TrackPoint"
        MatchDevicePath "/dev/input/event*"
        Option          "EmulateWheel"          "true"
        Option          "EmulateWheelButton"    "2"
        Option          "XAxisMapping"          "6 7"
        Option          "YAxisMapping"          "4 5"
 EndSection

50-twofingerscroll.conf
 Section "InputClass"
        Identifier      "two finger scrolling"
        Driver          "synaptics"
        MatchProduct    "SynPS/2 Synaptics TouchPad"
        MatchDevicePath "/dev/input/event*"
        Option          "VertTwoFingerScroll"   "on"
        Option          "HorizTwoFingerScroll"  "on"
        Option          "EmulateTwoFingerMinW"  "8"
        Option          "EmulateTwoFingerMinZ"  "40"
        Option          "TapButton1"            "1"
 EndSection

Adjust to your own needs. Read Touchpad Synaptics for more information.

To adjust the speed/sensitivity of the TrackPoint add these lines in a systemd tmpfile: 

/etc/tmpfiles.d/local.conf
w /sys/devices/platform/i8042/serio1/speed - - - - 180
w /sys/devices/platform/i8042/serio1/sensitivity - - - - 200

Possible range of values are 1-255.

NVIDIA Optimus

Bumblebee works as intended on models with NVIDIA Optimus

Optional kernel boot arguments

Using the following kernel boot parameters reduces battery drain: 

i915.i915_enable_rc6=1
i915.i915_enable_fbc=1
i915.lvds_downclock=1 
i915.semaphores=1

Troubleshooting

Media Keys

Media keys that work out of the box:

  • Wireless On/Off
  • Backlight Brightness settings
  • Thinklight
  • Mute

Media Keys that Do Not work out of the box:

  • Volume keys (Works out-of-the-box in Gnome)
  • Microphone mute (Requires a custom kernel patch)

You must find a workaround and bind the keys yourself for the rest of them.

Rebind Forward and Back keys

Keys forward and back (next to cursor keys) can be easily remapped to PageDown/PageUp.

Install xmodmap with the package xorg-server-utils

Create a ~/.Xmodmap file with content: 

keysym XF86Back = Page_Up
keysym XF86Forward = Page_Down

Add this line to your ~/.xinitrc to make it work: 

xmodmap ~/.Xmodmap

You can also re-map AudioPrev (Fn+Left) and AudioNext (Fn+Right) to Home/End: 

keysym XF86AudioNext = End
keysym XF86AudioPrev = Home
Note:
  • You have to log out for the changes to take effect.
  • The keys should work out of the box, at least on KDE.

Turn touchpad on and off

For some, the (Fn+F8) key does not switch the touchpad on and off. Here is a simple keybind to add to your ~/.xbindkeysrc for keys to quickly change your touchpad state. For these to take effect, run xbindkeysrc. This binds Fn+F8 to 'toggle the touchpad on and off'. (Tested in i3wm and xfce4, where normal Fn+F8 does not toggle the touchpad) 

# Toggle the Touchpad on|off
"synclient TouchpadOff=$(synclient -l | grep -ce TouchpadOff.*0)"
   m:0x0 + c:199
   XF86TouchpadToggle

Volume up/down not changing volume

Another quick keybind for ~/.xbindkeysrc to change the volume (which does not work on some DEs). Again, run xbindkeys for these to take effect. Taken from Xbindkeys 

#increase volume
"amixer set Master playback 1+"
   m:0x0 + c:123
   XF86AudioRaiseVolume

#decrase volume
"amixer set Master playback 1-"
   m:0x0 + c:122
   XF86AudioLowerVolume

Also, while the mute button works, I rebound it to interface with ALSA. 

# Toggle mute
"amixer set Master toggle"
   m:0x0 + c:121
   XF86AudioMute

Shutdown on battery

Some users have reported that the T420 was rebooting on shutdown on battery power. There have been quite a few attempts to fix this. Three are detailed here.

One way is to disable the module ehci_hcd. See Kernel_modules#Blacklisting for more information.

Or try disable Laptop-mode. Add !laptop-mode to the DAEMONS array in /etc/rc.conf: 

DAEMONS=(...!laptop-mode...)

This forum post details another way to have your computer not reboot on shutdown. Turning off the laptop-mode daemon causes battery life to suffer, so when on the move and in need of a simple way to shutdown, this seems to work better.

Hang on reboot

This is a problem on many laptops and can be fixed by blacklisting the e1000e kernel module.

No backlight controls

One user has reported that the brightness controls (fn+home, fn+end) did not work in some desktop environments. This could be fixed by adding the following kernel options: 

acpi_backlight=vendor acpi_osi=Linux

Also try to adjust the display in the console and not in X windows. If you don't have the keybindings correct in X, it will cause a problem. This can be bypassed if you use a virtual console to adjust the brightness.

See also

Retrieved from "https://wiki.archlinux.org/index.php?title=Lenovo_ThinkPad_T420&oldid=302087"