Re: [PATCH v2 0/4] Add max77620 charging & low battery support

Mark Zhang
2019-02-12T08:30:01Z

On 2/12/2019 4:04 PM, Lee Jones wrote:
> On Tue, 12 Feb 2019, Mark Zhang wrote:
>
>> On 2/7/2019 4:48 PM, Lee Jones wrote:
>>> On Tue, 29 Jan 2019, Mark Zhang wrote:
>>>
>>>> This patch set adds support for max77620 backup battery charging and
>>>> low battery monitoring.
>>>>
>>>> Changes in v2:
>>>> - Add devicetree binding documentation
>>>>
>>>> Mark Zhang (4):
>>>> mfd: max77620: Add backup battery charger support
>>>> mfd: max77620: add documentation for backup battery charging
>>>> mfd: max77620: Add low battery monitor support
>>>> mfd: max77620: add documentation for low battery monitoring
>>>>
>>>> .../devicetree/bindings/mfd/max77620.txt | 34 +++++
>>>> drivers/mfd/max77620.c | 137 +++++++++++++++++-
>>>
>>> All of this needs moving out to the correct subsystem.
>>>
>>> drivers/power/supply/max77620-battery.c looks right.
>>
>> Actually max77620 is not a power supply device. This patch set adds 2
>> features:
>> - Backup battery charger. The RTC in max77620 is supplied from a backup
>> battery and consumes 2.0uA when no other power sources are available. So
>> basically this is not a system battery charger, it's just for RTC.
>> - Low battery monitoring. This is for monitoring the system main battery
>> voltage, so max77620 can shutdown or reset the SoC accordingly. But I
>> think this doesn't conform the idea of "power supply" driver as well.
>
> Most other battery handling seems to happen in
> drivers/power/supply/*.battery*. If that's not the right location,
> then you need to find a place for it to go. MFDs do not provide
> useful functionality per say - that is the role of the child devices.
>

Understood. Looking at "enum power_supply_property", battery handling
drivers are able to get battery capacity/current
voltage/temperature/status/... and etc, which is making sense. But my
patch set doesn't do this kind of things at all so I think the power
supply framework doesn't fit here. Let me check other similar device
drivers... hope to get inspired. Thanks Lee.

Mark