From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [RFC PATCH] usb/acpi: Add support usb port power off mechanism for device fixed on the motherboard Date: Wed, 16 May 2012 08:08:46 -0700 Message-ID: <20120516150846.GB3293@kroah.com> References: <4FB348AB.5050308@intel.com> <20120516143958.GA612@kroah.com> <4FB3BF95.50600@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-yx0-f174.google.com ([209.85.213.174]:37872 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754118Ab2EPPIu (ORCPT ); Wed, 16 May 2012 11:08:50 -0400 Received: by yenm10 with SMTP id m10so762779yen.19 for ; Wed, 16 May 2012 08:08:50 -0700 (PDT) Content-Disposition: inline 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: Alan Stern , Sarah Sharp , Dan Williams , lenb@kernel.org, linux-acpi@vger.kernel.org, linux-usb@vger.kernel.org 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