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

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Message-ID: <VI1PR04MB53273342340E350BFFFDE12F8B530@VI1PR04MB5327.eurprd04.prod.outlook.com>
Date:   Wed, 18 Dec 2019 02:46:20 +0000
From:   Peter Chen <peter.chen@....com>
To:     Paul Cercueil <paul@...pouillou.net>
CC:     Sebastian Reichel <sre@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "od@...c.me" <od@...c.me>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: RE: [PATCH v2 3/3] power/supply: Add generic USB charger driver

 
> >>  >
> >>  >>  >>  +
> >>  >>  >>  +	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";
> >>  	};
> >>  };
> >>
> >>  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'.
> >>
> >
> > Thanks for explaining it.
> >
> > What's the user for this USB charger,  PMIC or what else? How the user
> > uses this USB charger interface?
> 
> It's exported as a standard charger, so it can be passed to client drivers through
> devicetree, and its online status can be retrieved from sysfs.
> 
 
Hi Paul,

If you would like to get role from usb-role-switch, the udc driver may probably have already worked.
There is a 'state' entry under the udc device to indicate USB Ch9 state. Try to see if it could
satisfy your requirement.

Peter