Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754859AbYLDEWu (ORCPT ); Wed, 3 Dec 2008 23:22:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751639AbYLDEWk (ORCPT ); Wed, 3 Dec 2008 23:22:40 -0500 Received: from hera.kernel.org ([140.211.167.34]:52972 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750942AbYLDEWj (ORCPT ); Wed, 3 Dec 2008 23:22:39 -0500 Message-ID: <49375A7F.10407@kernel.org> Date: Thu, 04 Dec 2008 13:20:15 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.17 (X11/20080922) MIME-Version: 1.0 To: Greg KH CC: linux-kernel@vger.kernel.org, stable@kernel.org, Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jeff Garzik Subject: Re: [patch 067/104] libata: improve phantom device detection References: <20081203193901.715896543@mini.kroah.org> <20081203195323.GP8950@kroah.com> In-Reply-To: <20081203195323.GP8950@kroah.com> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Thu, 04 Dec 2008 04:20:20 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1655 Lines: 42 > 2.6.27-stable review patch. If anyone has any objections, please let us know. > > ------------------ > From: Tejun Heo > > commit 6a6b97d360702b98c02c7fca4c4e088dcf3a2985 upstream. > > Currently libata uses four methods to detect device presence. > > 1. PHY status if available. > 2. TF register R/W test (only promotes presence, never demotes) > 3. device signature after reset > 4. IDENTIFY failure detection in SFF state machine > > Combination of the above works well in most cases but recently there > have been a few reports where a phantom device causes unnecessary > delay during probe. In both cases, PHY status wasn't available. In > one case, it passed #2 and #3 and failed IDENTIFY with ATA_ERR which > didn't qualify as #4. The other failed #2 but as it passed #3 and #4, > it still caused failure. > > In both cases, phantom device reported diagnostic failure, so these > cases can be safely worked around by considering any !ATA_DRQ IDENTIFY > failure as NODEV_HINT if diagnostic failure is set. > > Signed-off-by: Tejun Heo > Signed-off-by: Jeff Garzik > Signed-off-by: Greg Kroah-Hartman Alan thinks this patch could cause regression. Given that we're nearing the end of 2.6.28-rc cycles, I don't think it's critical to include this into 2.6.27-stable or at least it can wait a bit more. Thanks. -- tejun -- 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/