Re: [RFC PATCH] usb/acpi: Add support usb port power off mechanism for device fixed on the motherboard

Alan Stern
2012-05-16T15:12:17Z

On Wed, 16 May 2012, Lan Tianyu wrote:

> On 2012/5/16 22:39, Greg KH wrote:
> > On Wed, May 16, 2012 at 10:36:02AM -0400, Alan Stern wrote:
> >> On Wed, 16 May 2012, Lan Tianyu wrote:
> >>
> >>> Ok. Let me reconfirm the meaning of these opinions.
> >>>
> >>> "auto"
> >>> if port without device, turn off power directly.
> >>> if port with device, turn off power when the device is suspended.
> >>>
> >>> "on" the port's power must be on.
> >>>
> >>> "off" the port's power must be off.
> >>>
> >>> Right?
> >> Maybe the "auto" setting should be renamed "active". Then "auto" can
> >> be used for:
> >>
> >> If the port has a device, turn the power on.
> >> If the port doesn't have a device, turn the power off.
> > And plugging a new device into a port that was powered off is going to
> > cause the power to come back on, right?
> When the port was powered off, the connect-change event will not be
> detected and
> we don't know a device was plugged in. :(

Ah, yes. Okay, then I guess we _don't_ want a setting like the one I
suggested. The original proposal was good.

Alan Stern