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

Lan Tianyu
2012-05-16T14:54:17Z

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