Hey Sebastian, welcome back :-)
I've taken over work on this patchset from Matt.
On Wed, Mar 15, 2017 at 3:04 PM, Sebastian Reichel <sre@xxxxxxxxxx> wrote:
> Hi Liam & Matt,
>
> Sorry for my absence in the discussion. I skipped the previous
> iterations for now and start with this version.
>
> On Wed, Mar 15, 2017 at 12:26:46PM -0700, Liam Breck wrote:
>> From: Liam Breck <kernel@xxxxxxxxxxxxxxxxx>
>>
>> Documentation of static battery characteristics that can be defined
>> for batteries which cannot self-identify. This information is required
>> by fuel-gauge and charger chips for proper handling of the battery.
>>
>> Cc: Rob Herring <robh@xxxxxxxxxx>
>> Cc: devicetree@xxxxxxxxxxxxxxx
>> Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
>> Signed-off-by: Liam Breck <kernel@xxxxxxxxxxxxxxxxx>
>> ---
>> .../devicetree/bindings/power/supply/battery.txt | 45 ++++++++++++++++++++++
>> 1 file changed, 45 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/power/supply/battery.txt
>>
>> diff --git a/Documentation/devicetree/bindings/power/supply/battery.txt b/Documentation/devicetree/bindings/power/supply/battery.txt
>> new file mode 100644
>> index 0000000..0278617
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/power/supply/battery.txt
>> @@ -0,0 +1,45 @@
>> +Battery Characteristics
>
> Maybe add something like
>
> This device provides static battery information, that is usually
> available in the EEPROM of a smart battery. It's supposed to be
> used for batteries, which do not have their own EEPROM (or if its
> unusable).
OK.
>> +Required Properties:
>> + - compatible: Must be "fixed-battery"
Rob questioned the term "fixed". Shall we consider other terms --
simple-battery, plain-battery...?
>> +Optional Properties:
>> + - voltage-min-design-microvolt: drained battery voltage
>> + - energy-full-design-microwatt-hours: battery design energy
>> + - charge-full-design-microamp-hours: battery design capacity
>
> Looks fine to me.
>
>> +Because drivers surface properties in sysfs using names derived
>> +from enum power_supply_property, e.g.
>> +/sys/class/power_supply/<device>/charge_full_design, our
>> +battery properties must be named for the corresponding elements in
>> +enum power_supply_property, defined in include/linux/power_supply.h.
>
> This is Linux/implementation specific and does not belong
> into a DT binding document.
I just wrote on a thread for an earlier version of this patch:
"Sebastian proposed DT:battery specifically to be consumed by
power_supply_core. Allowing names in DT:battery and
power_supply_property to diverge would cause confusion and wasted
time, for no particular benefit. As there is no rationale to
reconsider the names of these fields for DT:battery, let's write that
into the docs."
>> +Batteries must be referenced by chargers and/or fuel-gauges
>> +using a phandle. The phandle's property should be named
>> +"monitored-battery".
>
> This looks fine.
>
>> +Driver code should call power_supply_get_battery_info() to obtain
>> +battery properties via monitored-battery. For details see:
>> + drivers/power/supply/power_supply_core.c
>> + drivers/power/supply/bq27xxx_battery.c
>
> This is also Linux/implementation specific and should be dropped.
We ought to mention how drivers are expected to consume DT:battery.
>> +Example:
>> +
>> + bat: battery {
>> + compatible = "fixed-battery";
>> + voltage-min-design-microvolt = <3200000>;
>> + energy-full-design-microwatt-hours = <5290000>;
>> + charge-full-design-microamp-hours = <1430000>;
>> + };
>> +
>> + charger: charger@11 {
>> + ....
>> + monitored-battery = <&bat>;
>> + ...
>> + };
>> +
>> + fuel_gauge: fuel-gauge@22 {
>> + ....
>> + monitored-battery = <&bat>;
>> + ...
>> + };
>> --
>> 2.9.3
>>
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