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

Greg KH
2012-05-16T15:08:50Z

On Wed, May 16, 2012 at 10:54:13PM +0800, 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. :(

Then that doesn't seem like a very good thing to ever do, right?

greg k-h