On Sun, Jan 29, 2017 at 6:46 PM, Liam Breck <liam@xxxxxxxxxxxxxxxxx> wrote:
> On Sun, Jan 29, 2017 at 6:39 PM, Sebastian Reichel <sre@xxxxxxxxxx> wrote:
>> Hi,
>>
>> On Sun, Jan 29, 2017 at 03:32:10PM -0800, Liam Breck wrote:
>>> On Sun, Jan 29, 2017 at 10:06 AM, Sebastian Reichel <sre@xxxxxxxxxx> wrote:
>>> > On Sun, Jan 22, 2017 at 02:22:12PM -0800, Liam Breck wrote:
>>> ...
>>> >> +Batteries must be referenced by chargers and/or fuel-gauges
>>> >> +using a phandle. The phandle's property should be named
>>> >> +"monitored-battery".
>>> >> +
>>> >> +Example:
>>> >> +
>>> >> + bat: battery {
>>> >> + compatible = "fixed-battery";
>>> >> + terminate-microvolt = <3700000>;
>>> >> + design-microwatt-hours = <5290000>;
>>> >> + design-microamp-hours = <1430000>;
>>> >> + };
>>> >> +
>>> >> + charger: charger@0 {
>>> >> + ....
>>> >> + monitored-battery = <&bat>;
>>> >> + ...
>>> >> + };
>>> >> +
>>> >> + fuel_gauge: fuel_gauge@0 {
>>> >> + ....
>>> >> + monitored-battery = <&bat>;
>>> >> + ...
>>> >> + };
>>> >
>>> > The charger stuff does does not integrate well with
>>> > pre-existing support for power-supplies property
>>> > described in
>>> > Documentation/devicetree/bindings/power/supply/power_supply.txt
>>> >
>>> > I think the proper chain would be:
>>> >
>>> > bat: battery {
>>> > compatible = "fixed-battery";
>>> > terminate-microvolt = <3700000>;
>>> > design-microwatt-hours = <5290000>;
>>> > design-microamp-hours = <1430000>;
>>> > };
>>> >
>>> > fuel_gauge: fuel_gauge@0 {
>>> > ...
>>> > monitored-battery = <&bat>;
>>> > power-supplies = <&charger>;
>>> > ...
>>> > };
>>> >
>>> > charger: charger@0 {
>>> > ...
>>> > };
>>> >
>>> > I added the power-supplies node to the fuel-gauge instead of the battery,
>>> > since fuel-gauge + fixed-battery is basically a smart battery.
>>>
>>> BQ24190 charger will need other params from a battery node. How does
>>> it get them in this scenario?
>>
>> It should be able to get all required properties from the bq27xxx.
>> Otherwise supporting smart batteries is impossible. What properties
>> do you need?
>
> These two, at a minimum:
>
> - precharge-microamps: maximum charge current during precharge
> phase (typically 20% of battery capacity)
>
> - termination-microamps: a charge cycle terminates when the
> battery voltage is above recharge threshold, and the current is below
> this setting (typically 10% of battery capacity)
The relevant docs, see section 9.5.1.4
http://www.ti.com/lit/ds/symlink/bq24190.pdf#31
BQ27xxx doesn't know about these parameters, but they are
characteristics of a fixed-battery, since the values are based on its
capacity. Smart batteries may have a circuit to limit current during
these phases. The BQ24190 charger is intended for dumb batteries :-)
So I believe letting charger and fuel-gauge both reference
monitored-battery is the right scheme.
~.~
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
