This documents the new battery controls and wear leveling support for Lenovo ThinkPad laptops. Signed-off-by: Ognjen Galic <smclt30p@xxxxxxxxx> --- Documentation/laptops/thinkpad-acpi.txt | 70 ++++++++++++++++++++++++- 1 file changed, 69 insertions(+), 1 deletion(-) diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt index 00b6dfed..3491d46f 100644 --- a/Documentation/laptops/thinkpad-acpi.txt +++ b/Documentation/laptops/thinkpad-acpi.txt @@ -1,6 +1,6 @@ ThinkPad ACPI Extras Driver - Version 0.25 + Version 0.27 October 16th, 2013 Borislav Deianov <borislav@xxxxxxxxxxxx> @@ -46,6 +46,9 @@ detailed description): - Fan control and monitoring: fan speed, fan enable/disable - WAN enable and disable - UWB enable and disable + - Battery wear control (battery start and stop threshold) + - Battery inhibit charge + - Battery force discharge A compatibility table by model and feature is maintained on the web site, http://ibm-acpi.sf.net/. I appreciate any success or failure @@ -1483,3 +1486,68 @@ Sysfs interface changelog: 0x030000: Thermal and fan sysfs attributes were moved to the hwmon device instead of being attached to the backing platform device. + + +Battery wear control (charge and stop thresholds) +-------------------------------------------------- + +Since Linux 4.17 tpacpi supports setting of charge start and stop thresholds on certain +Lenovo ThinkPad laptops. This feature is exposed via a new API from the ACPI battery driver +also new in Linux 4.17. + +The new battery API allows developers to extended the standard attributes offered by the +generic ACPI battery driver and add custom attributes from other drivers. thinkpad_acpi +leverages this API and exposes a few custom attributes for wear control of the battery. + +Wear control is designed to stop the charging of the battery at a certain threshold and thus +stop the cell from wearing out from constant charge cycles. So if you put the threshold at +50%, the charge will only charge the battery when it is below 50% and it will stop at 50%. + +A lower level is also exposed, thus creating a charger "dead zone", a zone where the charger does +nothing and the battery is in idle as if it was removed from the Thinkpad. + +For example, this is what happens when you set the values to 40% and 65%: + + ┌ Discharging ┐ + │ │ +[0%--------40% 65%-----------100%] Battery 1 + │ │ + └ Charging ┘ + +When plugged into AC and if the percentage is between 40% and 100% the battery is in idle. + +The attributes: +--------------- + +/sys/class/power_supply/BATx/charge_start_threshold [int, <0, >99] + +This sets the lower charge stop threshold for the battery. Its a integer and valid values are from +0% to 99%. + +/sys/class/power_supply/BATx/charge_stop_threshold [int, <1, >100] + +This sets the upper charge threshold for the battery. Its a integer and the value values are from +1% to 100%. + +Setting the lower limit to 0% and the upper limit to 100% disables the wear leveling control feature. + + +Battery charge inhibiting +-------------------------- + +Preventing the battery from charging is also available as a manual override over the settings. Its exposed via +the generic ACPI driver: + +/sys/class/power_supply/BATx/inhibit_charge [int, 1, 0] + +Setting it to 1 prevents the battery from charging. + +Battery force discharging +-------------------------- + +There is also support for AC overriding. This means that you can force the battery to discharge +even when AC is attached. This is also exposed via the generic ACPI driver: + +/sys/class/power_supply/BATx/force_discharge [int, 1, 0] + +Setting it to 1 forces the battery to discharge on AC. -- 2.17.0 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html