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

Lan Tianyu <tianyu.lan@xxxxxxxxx> · Wed, 16 May 2012 22:54:13 +0800

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. :(

greg k-h

--
Best Regards
Tianyu Lan
linux kernel enabling team

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