On 6 December 2012 06:57, Ming Lei <tom.leiming@xxxxxxxxx> wrote: > On Thu, Dec 6, 2012 at 12:49 AM, Roger Quadros <rogerq@xxxxxx> wrote: >> On 12/03/2012 05:00 AM, Ming Lei wrote: >>> On Mon, Dec 3, 2012 at 12:02 AM, Andy Green <andy.green@xxxxxxxxxx> wrote: >>>> On 02/12/12 23:01, the mail apparently from Ming Lei included: >>>> >>>>> Power controller is an abstract on simple power on/off switch. >>>>> >>>>> One power controller can bind to more than one device, which >>>>> provides power logically, for example, we can think one usb port >>>>> in hub provides power to the usb device attached to the port, even >>>>> though the power is supplied actually by other ways, eg. the usb >>>>> hub is a self-power device. From hardware view, more than one >>>>> device can share one power domain, and power controller can power >>>>> on if one of these devices need to provide power, and power off if >>>>> all these devices don't need to provide power. >>>> >>>> >>>> What stops us using struct regulator here? If you have child regulators >>>> supplied by a parent supply, isn't that the right semantic already without >>>> introducing a whole new thing? Apologies if I missed the point. >>> >>> There are two purposes: >>> >>> One is to hide the implementation details of the power controller because >>> the user doesn't care how it is implemented, maybe clock, regulator, gpio >>> and other platform dependent stuffs involved, so the patch simplify the usage >>> from the view of users. >>> >> >> Which user are you talking about? > > Here it is the usb port device. > > At least, there are many boards which have hardwired and self-powered usb > devices, so in theory they can benefits from the power controller. Maybe > only regulator and clock can't be covered completely for other boards. > > The patch can make usb port deal with the 'power controller' only, and make it > avoid to deal with regulators/clocks/... directly. > I am curious too, except for clocks and voltage supplies (regulators), what other external resources does a chip need ? -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
