From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Stern Subject: Re: [RFC PATCH] usb/acpi: Add support usb port power off mechanism for device fixed on the motherboard Date: Wed, 16 May 2012 11:12:16 -0400 (EDT) Message-ID: References: <4FB3BF95.50600@intel.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from iolanthe.rowland.org ([192.131.102.54]:54005 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754134Ab2EPPMR (ORCPT ); Wed, 16 May 2012 11:12:17 -0400 In-Reply-To: <4FB3BF95.50600@intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Lan Tianyu Cc: Greg KH , Sarah Sharp , Dan Williams , lenb@kernel.org, linux-acpi@vger.kernel.org, linux-usb@vger.kernel.org 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