From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755304Ab0ERA4g (ORCPT ); Mon, 17 May 2010 20:56:36 -0400 Received: from mail-gx0-f227.google.com ([209.85.217.227]:64342 "EHLO mail-gx0-f227.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753152Ab0ERA4e (ORCPT ); Mon, 17 May 2010 20:56:34 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=kQY7ia5pfIoAWQvUouJjGdFkua+blsp0dJijgQhlra4cP/KtCeS14NamK81f62iYA7 L+dOjeQmhHAziWuBJnnCdX65h8ZoUzbfT5rco/Lyck096Snz+IEC2yrDx6+wh0ctPWqW yQqZKKdX1rsJkeOThFBYP1yAnEiaEJjN7ySTg= Message-ID: <4BF1E5BE.9010000@gmail.com> Date: Mon, 17 May 2010 18:56:30 -0600 From: Robert Hancock User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-2.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: Andreas Herrmann CC: Yuhong Bao , venkatesh.pallipadi@intel.com, markh@compro.net, dmarkh@cfl.rr.com, andi@firstfloor.org, Linus Torvalds , alain@knaff.lu, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: Disable HPET MSI on ATI SB700/SB800 References: <87bphpd4rt.fsf@basil.nowhere.org> <4B32565E.6000501@compro.net> <20091223191806.GA3336@linux-os.sc.intel.com> <4B3270FE.5090607@compro.net> <1261600243.16916.56.camel@localhost.localdomain> <4B476E8D.1030308@compro.net> <20100121190952.GA32523@linux-os.sc.intel.com> <20100125171059.GB5041@alberich.amd.com> <20100517145943.GV5888@alberich.amd.com> In-Reply-To: <20100517145943.GV5888@alberich.amd.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/17/2010 08:59 AM, Andreas Herrmann wrote: > On Mon, Jan 25, 2010 at 06:10:59PM +0100, Andreas Herrmann wrote: >> On Fri, Jan 22, 2010 at 11:21:06PM -0800, Yuhong Bao wrote: >>> >>>> HPET MSI on platforms with ATI SB700/SB800 as they seem to have some >>>> side-effects on floppy DMA. Do not use HPET MSI on such platforms. >> >> Argh, will see what information I can find about this problem ... > > FYI. I've tried to trigger the publication of errata information for that > chipset. Finally this has happened. > > The discussed problem is indeed due to an erratum. See erratum #27 in > http://support.amd.com/us/Embedded_TechDocs/46837.pdf > > The suggested workaround for this is to disable HPET MSI if LPC > devices are used. I doubt that there is a convenient way for Linux to > find out whether LPC devices are used. Thus I think the only solution > to safely avoid the problem is the currently implemented quirk to > disable HPET MSI on this chipset. If one wanted, you could disable HPET MSI on this chipset only when a driver requests an ISA DMA channel. Then if there's no floppy or other LPC DMA device present, it can stay enabled. I don't know if it's worth the trouble, though.