linux-kernel - Re: [PATCH v3 8/8] dt-bindings: Add rt5033 mfd, regulator and charger

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Date:   Wed, 3 May 2023 21:33:49 +0200
From:   Jakob Hauser <jahau@...ketmail.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     Sebastian Reichel <sre@...nel.org>, Lee Jones <lee@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Beomho Seo <beomho.seo@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Stephan Gerhold <stephan@...hold.net>,
        Raymond Hackley <raymondhackley@...tonmail.com>,
        Pavel Machek <pavel@....cz>, Axel Lin <axel.lin@...ics.com>,
        ChiYuan Huang <cy_huang@...htek.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, phone-devel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v3 8/8] dt-bindings: Add rt5033 mfd, regulator and charger

Hi Krzysztof, Hi all,

On 02.05.23 12:59, Krzysztof Kozlowski wrote:
...
> Apologies for this, just very busy times. :)
> 

Thanks for letting me know. Take the time you need.

Writing towards the list:

I think there is a misunderstanding here.

The connector node provides information about the installed USB 
hardware. E.g. property "usb-role-switch" means "Indicates that the 
device is capable of assigning the USB data role (USB host or USB 
device) for a given USB connector [...]" [5]. To my understanding, in 
relation with a port node this actually says that this port has this 
capability. This is not relevant to the rt5033-charger driver.

The rt5033-charger driver needs to pair with the extcon chip because it 
needs the information about *external* connectors being attached [6].

Extcon devices like SM5502 or SM5504 are real hardware. I'm not adding 
new properties. The way of getting an excton device from the devicetree 
by phandle is part of the extcon subsystem:
  - function to get the excton device by phandle: [7]
  - line that's looking for the property "extcon": [8]

The connector node is the wrong approach, as far as I can tell on my 
current state of knowledge. It doesn't provide the information needed by 
the rt5033-charger driver.

[5] 
https://github.com/torvalds/linux/blob/v6.3/Documentation/devicetree/bindings/usb/usb-drd.yaml#L51-L55
[6] 
https://github.com/torvalds/linux/blob/v6.3/include/linux/extcon.h#L32-L60
[7] 
https://github.com/torvalds/linux/blob/v6.3/drivers/extcon/extcon.c#L1361-L1392
[8] 
https://github.com/torvalds/linux/blob/v6.3/drivers/extcon/extcon.c#L1381

Kind regards,
Jakob