Talk:Maintenance
In regard to the question about controlling the charge threshold from Linux: apparently this isn't controlled by some standard means such as an ACPI method, but rather by direct I/O port tweaking done by the Battery MaxiMiser driver for Windows. It would be very hard to figure this out without specs.
--Thinker 17:56, 2 Oct 2005 (CEST)
maybe it would be possible to use a windows tool like SoftICE to capture the communication required to set the treshholds? as soon as we have some sort of specification adding support for it to the kernel should be rather trivial. --gst
http://mailman.linux-thinkpad.org/pipermail/linux-thinkpad/2005-September/029556.html --gst
I see that when the charge threshold is set to a high value in Windows, charging is stopped even past reboots (including into Linux), battery changes and AC power loss. The only thing that resumes charging (other than changing the setting under Windows) is disconnection of the AC power while the laptop is turned off.
Another data point: it seems that charging enable/disable is done automatically in hardware based on the configured thresholds. Some forum posts suggested it's done by software monitoring, but I checked and it does work under Linux after rebooting from Windows.
In light of these, it seems the charge threshold behavior is implemented in the embedded controller, so the thresholds are probably stored there (rather than in RAM, CMOS or the battery). However, I can't see any obvious corresponding field in /proc/acpi/ibm/ecdump.
--Thinker 19:17, 6 Nov 2005 (CET)
