Re: [PATCH V4] drivers/rtc/rtc-palmas.c: support for backup batterycharging

From: Laxman Dewangan
Date: Wed Aug 07 2013 - 14:32:41 EST

On Wednesday 07 August 2013 10:08 PM, Mark Rutland wrote:
On Wed, Aug 07, 2013 at 11:29:52AM +0100, Laxman Dewangan wrote:
+Optional properties:
+- ti,back-battery-charge-enable: The Palmas series device like TPS65913 or
+ TPS80036 supports the battery backup for powering the RTC when main
+ battery is removed or in very low power state. This flag will enable
+ the backup battery charging.
I don't like the wording here as it implies that an OS *must* charge the
device, rather than that it *can* charge the device. How about:

- ti,backup-battery-chargeable: There is a chargeable backup battery

The *org* property tells whether charging should be enable or not. This is enabled during init and it is not the runtime configuration for enable/disable.
By saying "backup-battery-chargeable" means it need other interface/calls to start charging. It does not reflect that charging will be enabled by default.

+- ti,back-battery-charge-low-current: Configure lower charging current. Device
+ supports the charging current as < 100mA or >100mA. Low current will
+ set as <100mA.
This is somewhat unclear as it reads as a runtime configuration choice,
rather than some instances of the device only support being changed at
low currents (as I assume is the case?). How about:

- ti,backup-battery-low-current: The backup battery is only chargeable
at currents below 100mA.

Hmm.. I think even if battery can be charge for more than 100mA, there is choice of configure it for less than 100mA.

What happens if we charge at the wrong current?
Not much sure but I think it can create battery damage.

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