From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [Bug 14310] [bisected] 2.6.31 regression sis5513 PIO Mode 0 hang Date: Fri, 06 Nov 2009 04:52:04 -0800 (PST) Message-ID: <20091106.045204.64357638.davem@davemloft.net> References: <200910270835.n9R8ZRB2007651@demeter.kernel.org> <200911051654.27880.bzolnier@gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:46883 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758875AbZKFMvj (ORCPT ); Fri, 6 Nov 2009 07:51:39 -0500 In-Reply-To: <200911051654.27880.bzolnier@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: bzolnier@gmail.com Cc: bugzilla-daemon@bugzilla.kernel.org, linux-ide@vger.kernel.org From: Bartlomiej Zolnierkiewicz Date: Thu, 5 Nov 2009 16:54:27 +0100 > The problem is that the change in the debug patch affects all host drivers > and at this moment is not safe enough neither for -stable nor for -rc. > > Somebody needs to go and review all host drivers and their usage of ->media > field for tuning logic present in ->set_pio_mode implementations first. The drivers which do this are: drivers/ide/alim15x3.c drivers/ide/it8172.c drivers/ide/it8213.c drivers/ide/pdc202xx_old.c drivers/ide/piix.c drivers/ide/qd65xx.c drivers/ide/sis5513.c drivers/ide/slc90e66.c While the majority of them seem to use it to decide whether to enable prefetching or not, alim15x3.c uses the ->media value to decide whether to turn on the ATA or the ATAPI FIFO. I don't think it's safe to call ->set_pio_mode() until we actually know the media type. I suppose we could guard the prefetch/FIFO changes in these drivers with a test like: if (!(hwif->port_flags & IDE_PFLAG_PROBING)) or something like that. But in this stage of the game, it's just too risky and reverting the early PIO0 commit is the best way to go. I'll do that now.