Re: [PATCH 1/5] dt-bindings: connector: add fixed-batteries property

Amit Sunil Dhamne
2025-03-15T00:56:40Z

Hi Krzysztof,

On 3/13/25 1:48 AM, Krzysztof Kozlowski wrote:
> On Wed, Mar 12, 2025 at 04:42:01PM -0700, Amit Sunil Dhamne wrote:
>> Add a new "fixed-batteries" DT property to connector class. This
>> property is populated with nodes associated with battery type power
>> supplies powering the USB PD connector. This is needed by the Type-C
>> Port Manager (TCPM) to query psy properties which are used to feed
> What is "psy" in terms of bindings?
In terms of bindings this should be a phandle to a device that
owns/manages the battery (whose driver will eventually call
devm_power_supply_register to register the battery). This could be a
fuel-guage ("sprd,sc2731-fgu", say), charger ("ti,bq24190") or a
platform device ("cw2015") containing "monitored-battery" property to
manage the simple battery.
>> Battery_Status & Battery_Capacity AMS.
>>
>> Signed-off-by: Amit Sunil Dhamne <amitsd@google.com>
>> ---
>> Documentation/devicetree/bindings/connector/usb-connector.yaml | 8 ++++++++
>> Documentation/devicetree/bindings/usb/maxim,max33359.yaml | 1 +
>> 2 files changed, 9 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/connector/usb-connector.yaml b/Documentation/devicetree/bindings/connector/usb-connector.yaml
>> index 11e40d225b9f3a0d0aeea7bf764f1c00a719d615..5e15bc060f5a2cfce842f83de738f1e8bae3ce2d 100644
>> --- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
>> +++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
>> @@ -300,6 +300,14 @@ properties:
>> $ref: /schemas/types.yaml#/definitions/uint8-array
>> maxItems: 4
>>
>> + fixed-batteries:
>> + description: Contains references to nodes associated with battery type power
>> + supplies powering the USB PD device. These batteries are fixed type and
> What is a "battery type power supply"? If you just link here batteries,
> then we have type for it - monitored-battery - but I doubt connector has
> direct connection to the battery.
Regarding "nodes associated with battery type power supplies", I meant
something like a fuel guage or a charger OR platform device with
"monitored-battery" that will manage the battery lifecycle. If I use
monitored-battery for this, I will be restricted to only querying 1
simple battery. Also, I don't mean PD connector device to be a fuel
guage or charger that manages a specific battery. It should just be able
to query any FG/Chg for the battery status to relay that info to the
connector's port partner.

The intent of the patchset & this change is for the USB Type C protocol
manager module (that consumes these bindings) to be able to get info
(such as State of charge, design capacity, etc) from drivers that manage
the battery/batteries in the system. In order for such info to propagate
I need to hook up the references of these battery manager devices (fuel
guages, etc.) to connector.

I have addressed the connector <-> battery question in the cover letter.

> If you mean chargers, the OF graph is already there for this and no need
> for this patch.

No I don't mean just chargers in this case. Also, I didn't follow you on
the OF graph. Please can you explain further?

>
>> + not hot swappable.
>> + minItems: 1
>> + maxItems: 4
>> + $ref: /schemas/types.yaml#/definitions/phandle-array
>> +
>> dependencies:
>> sink-vdos-v1: [ sink-vdos ]
>> sink-vdos: [ sink-vdos-v1 ]
>> diff --git a/Documentation/devicetree/bindings/usb/maxim,max33359.yaml b/Documentation/devicetree/bindings/usb/maxim,max33359.yaml
>> index 3de4dc40b79192b60443421b557bd2fb18683bf7..66c99f0131f074f1c08e31d7481f555647e3b2f8 100644
>> --- a/Documentation/devicetree/bindings/usb/maxim,max33359.yaml
>> +++ b/Documentation/devicetree/bindings/usb/maxim,max33359.yaml
>> @@ -75,6 +75,7 @@ examples:
>> PDO_FIXED(9000, 2000, 0)>;
>> sink-bc12-completion-time-ms = <500>;
>> pd-revision = /bits/ 8 <0x03 0x01 0x01 0x08>;
>> + fixed-batteries = <&batt1 &batt2>;
> Two phandles, so two <>.

Ack. Will fix it in the next revision.

Thanks,

Amit

> Best regards,
> Krzysztof
>