Re: [RFC PATCH v2 1/5] dt-bindings: battry: add new battery parameters

[Rob Herring <robh@kernel.org>]

On Fri, Feb 14, 2020 at 09:30:05AM +0200, Matti Vaittinen wrote:
> Add:
> 
>  - tricklecharge-current-microamp:
> 
> Some chargers have 3 charging stages. First one when battery is almost
> empty is often called as trickle-charge. Last state when battery has been
> "woken up" is usually called as fast-charge. In addition to this some
> chargers have a 'middle state' which ROHM BD99954 data-sheet describes as
> pre-charge. Some batteries can benefit from this 3-phase charging
> [citation needed].

For car batteries at least, trickle charge is to keep battery full. But 
maybe in that context, it would be 'charge-term-current-microamp'.

I'm just concerned that we end up with multiple properties that mean the 
same thing. I think you're okay here.

> Introduce tricklecharge-current-microamp so that batteries can give
> charging current limit for all three states.
> 
>  - precharge-upper-limit-microvolt:
> 
> When battery voltage has reached certain limit we change from
> trickle-charge to next charging state (pre-charge for BD99954). Allow
> battery to specify this limit.
> 
>  - re-charge-voltage-microvolt:
> 
> Allow giving a battery specific voltage limit for chargers which can
> automatically re-start charging when battery has discharghed down to
> this limit.
> 
> - over-voltage-threshold-microvolt
> 
> Allow specifying voltage threshold after which the battery is assumed to
> be faulty.
> 
> Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
> ---
>  Documentation/devicetree/bindings/power/supply/battery.txt | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/power/supply/battery.txt b/Documentation/devicetree/bindings/power/supply/battery.txt
> index 5c913d4cf36c..7da044273e08 100644
> --- a/Documentation/devicetree/bindings/power/supply/battery.txt
> +++ b/Documentation/devicetree/bindings/power/supply/battery.txt
> @@ -11,15 +11,21 @@ different type. This prevents unpredictable, potentially harmful,
>  behavior should a replacement that changes the battery type occur
>  without a corresponding update to the dtb.
>  
> +Please note that not all charger drivers respect all of the properties.
> +
>  Required Properties:
>   - compatible: Must be "simple-battery"
>  
>  Optional Properties:
> + - over-voltage-threshold-microvolt: battery over-voltage limit
> + - re-charge-voltage-microvolt: limit to automatically start charging again
>   - voltage-min-design-microvolt: drained battery voltage
>   - voltage-max-design-microvolt: fully charged battery voltage
>   - energy-full-design-microwatt-hours: battery design energy
>   - charge-full-design-microamp-hours: battery design capacity
> + - tricklecharge-current-microamp: current for trickle-charge phase

trickle-charge-...

>   - precharge-current-microamp: current for pre-charge phase
> + - precharge-upper-limit-microvolt: limit when to change to constant charging
>   - charge-term-current-microamp: current for charge termination phase
>   - constant-charge-current-max-microamp: maximum constant input current
>   - constant-charge-voltage-max-microvolt: maximum constant input voltage
> -- 
> 2.21.0
> 
> 
> -- 
> Matti Vaittinen, Linux device drivers
> ROHM Semiconductors, Finland SWDC
> Kiviharjunlenkki 1E
> 90220 OULU
> FINLAND
> 
> ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
> Simon says - in Latin please.
> ~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
> Thanks to Simon Glass for the translation =]