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. Thanks, -- Ming Lei -- 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
