Re: [PATCH v2 08/14] power: supply: Add power_supply_set_input_current_limit_from_supplier helper

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 16-08-17 17:54, Tony Lindgren wrote:
> * Hans de Goede <hdegoede@redhat.com> [170815 13:06]:
>> On some devices the USB Type-C port power (USB PD 2.0) negotiation is
>> done by a separate port-controller IC, while the current limit is
>> controlled through another (charger) IC.
>>
>> It has been decided to model this by modelling the external Type-C
>> power brick (adapter/charger) as a power-supply class device which
>> supplies the charger-IC, with its voltage-now and current-max representing
>> the negotiated voltage and max current draw.
>>
>> This commit adds a power_supply_set_input_current_limit_from_supplier
>> helper function which charger power-supply drivers can call to get
>> the max-current from their supplier and have this applied
>> through their set_property call-back to their input-current-limit.
> 
> Hmm so can this also be used for the USB gadget subsystem
> to tell charge controller when it's OK to enable 500mA
> charging after enumeration?

I'm not sure that that would be best modeled this way. Perhaps
the phy-driver can directly control the gpio you have for that,
that seems better then trying to solve this with cross subsystem
calls which are always tricky.

> FYI, that's controlled by the bq24190 pin named OTG that should
> be only set high after enumeration. Any ideas how that is wired
> on your device? Does it connect to the USB PHY or to a GPIO
> line?

I believe it is just hardwired to be logical high all the time
on my board.

Regards,

Hans