From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] libata: Forcing PIO0 mode on reset must not freeze system Date: Mon, 11 Feb 2008 19:49:17 +0900 Message-ID: <47B0282D.2050703@gmail.com> References: <20080210195556.GA5261@homac> <47AFB4DB.1000204@gmail.com> <20080211102907.GC4646@homac.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080211102907.GC4646@homac.suse.de> Sender: linux-kernel-owner@vger.kernel.org To: Tejun Heo , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, alan@redhat.com, jeff@garzik.org List-Id: linux-ide@vger.kernel.org Hello, Holger Macht wrote: >> In the above example, even the reset sequence itself can cause hang if >> the hardware is implemented slightly differently. The reason why >> set_piomode() locks up but reset sequence doesn't is simple dumb luck. > > Another thing, whether it's poor luck or not, it worked like this than at > least 2.6.22. And it was _heavily_ tested. The above commit broke it > between 2.6.24-rc1 and 2.6.24-rc2, which is at least a regression. Yes, in a sense but the change is in the area where there's no defined behavior, so I don't think it's a good idea to revert the change here. Let's concentrate on finding the proper solution. Thanks. -- tejun