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

[Paul Cercueil]

Hi Peter,


Le mer., déc. 18, 2019 at 02:46, Peter Chen <peter.chen@xxxxxxx> 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@13440000 {
> >  >>  	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.

This is not the proper way to retrieve charger status.
Linux supports chargers through the power supply subsystem, that's 
where it should be exported.

Cheers,
-Paul