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. Another is that several users may share one power controller, and the introduced power controller can help users to use it. Also the power controller is stored as device resource, not any new stuff added into 'struct device', and all users of the power controller needn't write code to operate device resource things too. 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
