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SubjectRE: [PATCH v2 3/3] power/supply: Add generic USB charger driver
Hi Peter,


Le mer., déc. 18, 2019 at 02:46, Peter Chen <peter.chen@nxp.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@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


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