linux-kernel - Re: [PATCH v2 3/3] power/supply: Add generic USB charger driver

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Date:   Thu, 19 Dec 2019 13:38:45 -0800
From:   Rob Herring <robh@...nel.org>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Peter Chen <peter.chen@....com>,
        Sebastian Reichel <sre@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>, od@...c.me,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v2 3/3] power/supply: Add generic USB charger driver

On Mon, Dec 16, 2019 at 11:52:05AM +0100, Paul Cercueil wrote:
> Hi Peter,
> 
> 
> Le lun., déc. 16, 2019 at 01:24, Peter Chen <peter.chen@....com> a écrit :
> > 
> > >  >>  +
> > >  >>  +	desc = &charger->desc;
> > >  >>  +	desc->name = "usb-charger";
> > >  >>  +	desc->properties = usb_charger_properties;
> > >  >>  +	desc->num_properties = ARRAY_SIZE(usb_charger_properties);
> > >  >>  +	desc->get_property = usb_charger_get_property;
> > >  >>  +	desc->type = POWER_SUPPLY_TYPE_USB;
> > >  >
> > >  > What's your further plan for this generic USB charger?
> > >  > To support BC1.2, we need to know charger type, and how we could
> > > get
> > >  > it?
> > >  >
> > >  > Peter
> > > 
> > >  Well I don't really know. The USB role framework does not give any
> > > info about
> > >  what's plugged.
> > > 
> > 
> > What's the use case for this patch set? How it be used?
> 
> My devicetree:
> 
> usb_otg: usb@...40000 {
> 	compatible = "ingenic,jz4770-musb", "simple-mfd";
> 	reg = <0x13440000 0x10000>;
> 	[...]
> 
> 	usb-role-switch;
> 
> 	connector {
> 		compatible = "gpio-usb-b-connector", "usb-b-connector";
> 		label = "mini-USB";
> 		type = "mini";
> 
> 		id-gpios = <&gpf 18 GPIO_ACTIVE_HIGH>;
> 		vbus-gpios = <&gpb 5 GPIO_ACTIVE_HIGH>;
> 		[...]
> 	};
> 
> 	usb_charger: usb-charger {
> 		compatible = "usb-charger";

What h/w device is this?

> 	};
> };
> 
> The new gpio-usb-connector driver uses the ID/VBUS GPIOs to detect in which
> state (device, host, unconnected) a OTG connector is. However, that means I
> cannot use the standard gpio-charger driver to detect the presence of a
> charger based on the state of the VBUS gpio, since it's already requested
> here. So the point of this patchset is to provide an alternative to
> gpio-charger that works with OTG controllers compatible with
> 'usb-role-switch'.

Why not fix gpio-charger or make whatever 'owns' vbus-gpios to register 
a charger device?

I guess you could have Vbus sensing with no charging capability, but 
that sounds like a new property, not a node to me.

Rob