From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lan Tianyu Subject: Re: [RFC PATCH] usb/acpi: Add support usb port power off mechanism for device fixed on the motherboard Date: Sat, 12 May 2012 02:18:54 +0800 Message-ID: <4FAD580E.2010301@intel.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mga09.intel.com ([134.134.136.24]:10469 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756764Ab2EKSYO (ORCPT ); Fri, 11 May 2012 14:24:14 -0400 In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Alan Stern Cc: Sarah Sharp , lenb@kernel.org, gregkh@linuxfoundation.org, linux-acpi@vger.kernel.org, linux-usb@vger.kernel.org On 2012=E5=B9=B405=E6=9C=8812=E6=97=A5 01:44, Alan Stern wrote: > On Sat, 12 May 2012, Lan Tianyu wrote: > >> The power saving depends on devices. I test a usb3.0 ssd. The p= ower saving of >> power off is about 2.2w more than just selective suspend. In theory,= power >> off can help to save remaining power after selective suspend. > > That's a lot of power! Suspended USB devices aren't supposed to > consume more than 2.5 mA of bus current, which at 5 V amounts to<=3D > 0.0125 W. Does the port really use that much? Or does the SSD have = a > separate power supply that it disables when port power is removed? The device consumes about 3.1w. The selective suspend can cut down 0.7-= 0.9w After power off port, all power will removed. I test all the motherboard power consumption and get the result. From lsusb, it's self-powered. lsusb Bus 003 Device 006: ID 174c:55aa ASMedia Technology Inc. Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.10 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x174c ASMedia Technology Inc. idProduct 0x55aa bcdDevice 1.00 iManufacturer 2 012345678901234567890123456789012345678901= 23 iProduct 3 012345678901234567890123456789012345678901= 234567 iSerial 1 0123456789ABCDEF019F bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xc0 Self Powered MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 8 Mass Storage bInterfaceSubClass 6 SCSI bInterfaceProtocol 80 Bulk (Zip) iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x02 EP 2 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Device Status: 0x0001 Self Powered --=20 Best Regards Tianyu Lan linux kernel enabling team -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html