From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932313Ab2HOT54 (ORCPT ); Wed, 15 Aug 2012 15:57:56 -0400 Received: from ogre.sisk.pl ([193.178.161.156]:40861 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932193Ab2HOT5v (ORCPT ); Wed, 15 Aug 2012 15:57:51 -0400 From: "Rafael J. Wysocki" To: Bjorn Helgaas Subject: Re: [PATCH] PCI / ACPI: Do not request control of ASPM if the BIOS has disabled it Date: Wed, 15 Aug 2012 22:03:48 +0200 User-Agent: KMail/1.13.6 (Linux/3.5.0+; KDE/4.6.0; x86_64; ; ) Cc: Len Brown , ACPI Devel Mailing List , LKML , linux-pci@vger.kernel.org, Wei Kong , Jean Delvare , Matthew Garrett References: <201205242245.45888.rjw@sisk.pl> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201208152203.48377.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday, August 15, 2012, Bjorn Helgaas wrote: > On Thu, May 24, 2012 at 2:45 PM, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki > > > > We want to report that the kernel supports ASPM to the BIOS even if > > the BIOS signals us that it doesn't. So, we need the flags to include > > (OSC_ACTIVE_STATE_PWR_SUPPORT | OSC_CLOCK_PWR_CAPABILITY_SUPPORT) > > before calling acpi_pci_osc_support(root, flags) in > > acpi_pci_root_add() (unless there's a command line telling us that > > ASPM is not to be supported). > > > > However, knowing that the BIOS doesn't support ASPM, we shouldn't > > request the control of it, so we should remove > > (OSC_ACTIVE_STATE_PWR_SUPPORT | OSC_CLOCK_PWR_CAPABILITY_SUPPORT) > > from the flags before calling acpi_pci_osc_control_set() in those > > cases. Failing to do so causes the evaluation of _OSC for the PCI > > root bridge to return error codes on some systems where it should > > work correctly. > > > > Reported-and-tested-by: Wei Kong > > Signed-off-by: Rafael J. Wysocki > > --- > > > > -stable material, I think. > > Len, since you've applied recent patches in this area, can you take > care of this, too? No, please don't. I'd discussed that with Matthew and we concluded that it would break things sometimes. Please disregard it (and sorry for not saying that earlier). Thanks, Rafael > > --- > > drivers/acpi/pci_root.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > Index: linux/drivers/acpi/pci_root.c > > =================================================================== > > --- linux.orig/drivers/acpi/pci_root.c > > +++ linux/drivers/acpi/pci_root.c > > @@ -574,6 +574,10 @@ static int __devinit acpi_pci_root_add(s > > if (flags != base_flags) > > acpi_pci_osc_support(root, flags); > > > > + if (!pcie_aspm_enabled()) > > + flags &= ~(OSC_ACTIVE_STATE_PWR_SUPPORT | > > + OSC_CLOCK_PWR_CAPABILITY_SUPPORT); > > + > > if (!pcie_ports_disabled > > && (flags & ACPI_PCIE_REQ_SUPPORT) == ACPI_PCIE_REQ_SUPPORT) { > > flags = OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL > >