Instead of Intro
ThinkPad`s have been always famous for the amazing hardware compatibility with Linux. But seems this time has gone and owners of new ThinkPad`s like ThinkPad X230, T430 and of some other may have started experiencing some uncomfortable changes. The one of the such changes is inability to use tp_smapi module to set battery thresholds.Battery charge threshold might be important for you if you want extend the battery's health. They are used to keep batteries partially charged.
I am as an owner of brand new ThinkPad x230 run into the impossibility to load tp_smapi module for my primary Debian (Testing) GNU/Linux as well as to set above mentioned thresholds. Here will be a safe workaround to fix the regression. It must work as well for Ubuntu Linux.
For the previous versions of ThinkPad`s it was simply enough to put desired integers to /sys/devices/platform/smapi/BAT{0,1}/{start,stop}_charge_thresh files to make these thresholds work. Currently there are no such special files anymore; since tp_acpi loading is failed. At least for the newest ThinkPad`s. Fortunately there is an alternative way: to set these values directly through the kernel's ACPI subsystem not ThinkPad brand controller's interface.
There is a module called acpi_call which was originally designed for easy switching video adapters in dual graphics environments. It provides a convenient interface for sending any command to ACPI subsystem; literally "call ACPI for some request". But which command to send to request a change of charge thresholds? Actually it does not matter because you should not do it by yourself. There is a special tool called tpacpi-bat (the part of tpbattstat-applet) which will do it for you.
Solution: all steps together
The only things we need to make ThinkPad`s charge thresholds work in Debian/Ubuntu are:
- Install acpi_call module;
- Install tpacpi_bat script;
- Configure thresholds setting on system boot-up;
acpi_call for Debian/Ubuntu
acpi_call is not included to standard Debian/Ubuntu repositories. The only way is to build it by yourself. Since I am a bit lazy about keeping in mind that with each kernel update I should rebuild acpi_call module I decided to write a simple script which will register and install it as a DKMS module.The script could be retrieved from my git repository. The only requirement for running it is a root permission. If some packages required to build are missing you will be notified. Run it with 'run' argument and the script will do the following for you:
- Retrieve acpi_call sources from the main git repository;
- Register it as a DKMS module;
- Install acpi_module to your Debian/Ubuntu system.
tpacpi_bat
tpacpi_bat is also not included to standard Debian/Ubuntu repositories. It could be grabbed from the author's git repository. The script depends on Perl only and could be put anywhere on the system, e.g. to /usr/local/bin.
Thresholds on boot-up
To make charge thresholds set on system boot-up:
- acpi_call entry must be added to /etc/modules
- The following commands must be added to /etc/rc.local:
/usr/local/tpacpi-bat -v startChargeThreshold 0 N /usr/local/tpacpi-bat -v stopChargeThreshold 0 K
where N and K are integers in percent of full battery capacity.
Enjoy! Thanks to this ThinkPad's batteries might be a bit healthy :).
