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

[Tony Lindgren <tony@atomide.com>]

* Hans de Goede <hdegoede@redhat.com> [170816 10:38]:
> 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.

I don't think the phy driver knows either when the system
has enumerated as a gadget..

> > 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.

OK thanks for checking.

Tony