From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753617Ab0FVSn6 (ORCPT ); Tue, 22 Jun 2010 14:43:58 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:38665 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753055Ab0FVSn4 (ORCPT ); Tue, 22 Jun 2010 14:43:56 -0400 From: "Rafael J. Wysocki" To: Jesse Barnes , Matthew Garrett Subject: Re: [PATCH] ACPI: Disable ASPM if the platform won't provide _OSC control for PCIe Date: Tue, 22 Jun 2010 20:42:14 +0200 User-Agent: KMail/1.13.3 (Linux/2.6.35-rc3-rjw+; KDE/4.4.3; x86_64; ; ) Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org References: <1277220343-25168-1-git-send-email-mjg@redhat.com> <201006222017.30023.rjw@sisk.pl> <20100622112908.4122ceb2@virtuousgeek.org> In-Reply-To: <20100622112908.4122ceb2@virtuousgeek.org> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201006222042.14774.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, June 22, 2010, Jesse Barnes wrote: > On Tue, 22 Jun 2010 20:17:29 +0200 > "Rafael J. Wysocki" wrote: > > > On Tuesday, June 22, 2010, Matthew Garrett wrote: > > > The PCI SIG documentation for the _OSC OS/firmware handshaking interface > > > states: > > > > > > "If the _OSC control method is absent from the scope of a host bridge > > > device, then the operating system must not enable or attempt to use any > > > features defined in this section for the hierarchy originated by the host > > > bridge." > > > > > > The obvious interpretation of this is that the OS should not attempt to use > > > PCIe hotplug, PME or AER - however, the specification also notes that an > > > _OSC method is *required* for PCIe hierarchies, and experimental validation > > > with An Alternative OS indicates that it doesn't use any PCIe functionality > > > if the _OSC method is missing. That arguably means we shouldn't be using > > > MSI or extended config space, but right now our problems seem to be limited > > > to vendors being surprised when ASPM gets enabled on machines when other > > > OSs refuse to do so. So, for now, let's just disable ASPM if the _OSC > > > method doesn't exist or refuses to hand over PCIe capability control. > > > > > > Signed-off-by: Matthew Garrett > > > > Acked-by: Rafael J. Wysocki > > Applied to my linux-next branch, thanks. I think it's 2.6.35 (and probably -stable) material, these problems aleady happen in the field. Matthew, what do you think? Rafael