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

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Message-ID: <3a33dab7-87b2-4b74-b138-e368d4cbc358@kernel.org>
Date: Sun, 16 Mar 2025 17:49:46 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Amit Sunil Dhamne <amitsd@...gle.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Badhri Jagan Sridharan <badhri@...gle.com>,
 Sebastian Reichel <sre@...nel.org>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <len.brown@...el.com>,
 Pavel Machek <pavel@...nel.org>, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
 linux-pm@...r.kernel.org, RD Babiera <rdbabiera@...gle.com>,
 Kyle Tso <kyletso@...gle.com>
Subject: Re: [PATCH 1/5] dt-bindings: connector: add fixed-batteries property

On 15/03/2025 01:56, Amit Sunil Dhamne wrote:
> 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 

So a charger? Please rephrain from putting Linux names into the bindings
description.

> 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@...gle.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 

The intent should be rather to accurately describe hardware and maybe
that's the problem - you focus how to bend it for your drivers.


Best regards,
Krzysztof