Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755751AbYHNN7J (ORCPT ); Thu, 14 Aug 2008 09:59:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751486AbYHNN64 (ORCPT ); Thu, 14 Aug 2008 09:58:56 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:40515 "EHLO gprs189-60.eurotel.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751447AbYHNN6z (ORCPT ); Thu, 14 Aug 2008 09:58:55 -0400 Date: Thu, 14 Aug 2008 15:50:21 +0200 From: Pavel Machek To: Oliver Neukum Cc: linux-pm@lists.linux-foundation.org, Alan Stern , James.Bottomley@hansenpartnership.com, Linux-pm mailing list , kernel list , teheo@novell.com Subject: Re: [linux-pm] Power management for SCSI Message-ID: <20080814135021.GE2262@elf.ucw.cz> References: <200808131821.30564.oneukum@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <200808131821.30564.oneukum@suse.de> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1387 Lines: 29 On Wed 2008-08-13 18:21:29, Oliver Neukum wrote: > Am Mittwoch 13 August 2008 17:44:46 schrieb Alan Stern: > > > All children that are USB must be powered down. We know in fact that most > > > drives don't care that the device is suspended. The problem was drive > > > enclosures that cut power upon suspension losing cached data. > > > > You misunderstood my question. ?Are there SCSI transports other than > > 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 autosuspending > the storage device (host) without telling the disks (devices) > > You could even argue that these storage devices violate the USB spec. Hmm... but suspended devices have very little power budget, right? So unless you have external power supply (2.5" frames generally don't), you can't really suspend and stay spinned up... -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/