From: Bjorn Helgaas <bhelgaas@google.com>
To: "Rafael J. Wysocki" <rjw@sisk.pl>, Len Brown <lenb@kernel.org>
Cc: ACPI Devel Mailing List <linux-acpi@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-pci@vger.kernel.org, Wei Kong <wkong@novell.com>,
Jean Delvare <jdelvare@suse.com>,
Matthew Garrett <mjg59@srcf.ucam.org>
Subject: Re: [PATCH] PCI / ACPI: Do not request control of ASPM if the BIOS has disabled it
Date: Wed, 15 Aug 2012 13:47:23 -0600 [thread overview]
Message-ID: <CAErSpo4LQsWH7eX=3YNSGUdZjNyMQeyoZPrx2ZUto3gWLYSWEQ@mail.gmail.com> (raw)
In-Reply-To: <201205242245.45888.rjw@sisk.pl>
On Thu, May 24, 2012 at 2:45 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
>
> 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 <wkong@novell.com>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
>
> -stable material, I think.
Len, since you've applied recent patches in this area, can you take
care of this, too?
> ---
> 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
next prev parent reply other threads:[~2012-08-15 19:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-24 20:45 [PATCH] PCI / ACPI: Do not request control of ASPM if the BIOS has disabled it Rafael J. Wysocki
2012-05-24 20:45 ` Matthew Garrett
2012-05-25 11:53 ` Jean Delvare
2012-08-15 19:47 ` Bjorn Helgaas [this message]
2012-08-15 20:03 ` Rafael J. Wysocki
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