From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754885AbZERTSt (ORCPT ); Mon, 18 May 2009 15:18:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751605AbZERTSl (ORCPT ); Mon, 18 May 2009 15:18:41 -0400 Received: from mailout02.t-online.de ([194.25.134.17]:34644 "EHLO mailout02.t-online.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751258AbZERTSl (ORCPT ); Mon, 18 May 2009 15:18:41 -0400 Date: Mon, 18 May 2009 21:12:07 +0200 From: Martin Lottermoser To: Bartlomiej Zolnierkiewicz Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org Subject: Re: PATA DMA problem leading to kernel panic on reading movie DVDs Message-ID: <20090518191207.GA7531@wanza.invalid> References: <20090517091224.GA8280@wanza.invalid> <4A10509C.603@gmail.com> <200905172135.10136.bzolnier@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200905172135.10136.bzolnier@gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ID: GWxvUqZF8h2pmHyApYx82FjjobkZLvnAZDeEJzeGEO12X6Zo3+nDKsgbLfupdCDgGk X-TOI-MSGID: f3d08477-48f9-4c78-89f5-5b8bafc5b300 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Sun, May 17, 2009 at 09:35:09PM +0200, Bartlomiej Zolnierkiewicz wrote: > Martin, this is one of ATAPI drives which support UDMA66 but have broken > cable detection. Since 2.6.26 we have a special quirk for it ide (commit > 3ced5c49bd2d1f2c7f769e3a54385883de63a652) and subsequent one in libata > (commit e9f3340673c1da32041f2a282b166c72cd78632e). > > In your system's case the cable detection doesn't seem to work properly > which in turn results in all kind of later problems. > > It could be that the quirk itself needs to be revised (I wonder if it was > originally tested with 40-wires cable) or maybe we need some other cable > detection fix... > > Please: > > * send 'hdparm --Istdout /dev/hdc' output > > * try 2.6.30-rc6 (maybe 2.6.29.3 oops has been fixed already and we just > need to backport it) > > also connecting the drive using 80-wires cable and getting another hdparm > output (+ seeing if it helps the other problems) would be very useful. I've done that now as well. Test runs with Debian's 2.6.26 and with 2.6.30-rc6 show no problems: no disabling of DMA, no kernel panic. The hdparm output ("hdparm --Istdout") is the same for a 40-wire cable and an 80-wire cable (checked under 2.6.26). This indicates that your hypothesis above that it's a cable detection problem is correct. Just out of curiosity: is this a bug on the drive's side or in the kernel? Or in other words: if the output of "hdparm -I" shows the drive as attached to be able to support UDMA4, is this a statement passed through unmodified from the drive or is this a deduction made by the kernel? I ask because under 2.6.22.9 and 2.6.23.14 I got a message that "host side 80-wire cable detection failed". Should anyone find a fix to correct/circumvent this problem in the kernel, I'ld be willing to test it on my system; just send a patch file or tell me where to pick it up. Regards, Martin Lottermoser -- Martin Lottermoser Martin.Lottermoser at _REMOVE_t-online.de Greifswaldstrasse 28 38124 Braunschweig http://home.vrweb.de/martin.lottermoser Germany