From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Neukum Subject: Re: [linux-pm] Power management for SCSI Date: Wed, 13 Aug 2008 18:21:29 +0200 Message-ID: <200808131821.30564.oneukum@suse.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: linux-pm@lists.linux-foundation.org Cc: Alan Stern , James.Bottomley@hansenpartnership.com, Pavel Machek , Linux-pm mailing list , kernel list , teheo@novell.com List-Id: linux-pm@vger.kernel.org Am Mittwoch 13 August 2008 17:44:46 schrieb Alan Stern: > > All children that are USB must be powered down. We know in fact tha= t most > > drives don't care that the device is suspended. The problem was dri= ve > > enclosures that cut power upon suspension losing cached data. >=20 > You misunderstood my question. =A0Are there SCSI transports other tha= n > USB sharing the requirement that all child devices must be suspended > before the link can be powered down? I dispute that USB in general has this property. Some storage devices need their caches flushed. USB itself is perfectly happy with autosuspe= nding the storage device (host) without telling the disks (devices) You could even argue that these storage devices violate the USB spec. Regards Oliver