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    SubjectRe: [ibm-acpi-devel] [RFC] Controlling the ThinkPad battery charger
    On Mon, May 9, 2011 at 11:29 AM, Henrique de Moraes Holschuh
    <hmh@hmh.eng.br> wrote:
    > On Mon, 09 May 2011, Andrew Lutomirski wrote:
    >> > The SBS interface exposes more data about the battery, including
    >> > per-cell-group voltage and pack microcontroller aging counters, alarms, and
    >> > the "needs to get through the fuel-gaugue reset procedure" semasphore.
    >>
    >> If I'm feeling really motivated, I'll look at that.  I'm currently
    >> more interested in the charging thresholds, though, which I think is
    >> independent of the choice of SBS vs ACPI to access the battery state.
    >> (From a quick glance at the SBS spec, you can inhibit charging
    >> entirely but you can't ask for thresholds.  I assume that the EC takes
    >> care of that.  If I'm wrong, please tell me, but SMAPI seems like a
    >> fine way to access the thresholds.)
    >
    > Yeah, SMAPI is the safest way to deal with all this.  It is an interface
    > layer that Lenovo is not fond of breaking (or touches very rarely.  Amounts
    > to the same in the end).
    >
    > SBS does not take care of thresholds, indeed.  The EC does (and I know how
    > to program the threshold in a few models, if you do want to test it in your
    > X220, I can send you the information.  It is safe to test if you use it
    > together with SMAPI to cross-check).

    That would be great. I think it's EC register 0x24 for the BAT0 stop
    threshold and EC register 0x25 for the BAT1 stop threshold. If you
    have any hints about the start threshold I can test them, but I
    suspect that, in the X220, the EC figures out the start threshold on
    its own.

    >
    > The SBS ACPI interface would be useful to provide a single driver that can
    > replace the ACPI battery one to deliver full functionality in one place.
    >

    I'll save that for later :)

    --Andy

    > --
    >  "One disk to rule them all, One disk to find them. One disk to bring
    >  them all and in the darkness grind them. In the Land of Redmond
    >  where the shadows lie." -- The Silicon Valley Tarot
    >  Henrique Holschuh
    >
    --
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