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    SubjectRe: power_supply class/framework question
    From
    On Mon, Aug 10, 2009 at 8:28 AM, Anton
    Vorontsov<avorontsov@ru.mvista.com> wrote:
    > On Mon, Aug 10, 2009 at 05:00:11PM +0200, Pavel Machek wrote:
    >> > I'm working on cleaning up some code to more correctly use the power
    >> > supply framework (have the battery driver receive notification from
    >> > the wall/usb power supplies, etc), and ran into a slight snag.  For
    >> > mobile usb powered devices, we need to know how much current can
    >> > safely be consumed by the charge circuit -- generally this is one of:
    >> > none, <500mA or 1000mA, which correspond to "no power supply", "usb
    >> > power supply", or "wall power supply".
    >>
    >> Actuallly, it is one of 'none', 100mA (min power USB has to supplly),
    >> 500mA (max powe USB can supply by spec), 1A (wall).
    >>
    >> > I can use power_supply_am_i_supplied() to determine if I'm receiving
    >> > power, but there's no way to determine either how much (if I have one
    >> > power supply that indicates max current available) or which supply (if
    >> > I define a separate "ac" and "usb" power supply).
    >>
    >> Should am_i_supplied() just return miliamps?
    >
    > Or enum power_supply_type, with the following priority:
    > mains (wall), usb, battery?

    Either of those would work, though in the case of USB, as Pavel
    correctly points out, we'd need to differentiate between
    non-enumerated and enumerated, so perhaps max available milliamps
    would be best. Or USB could just not indicate that it's supplied
    until after enumeration is successful.

    Brian
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