linux-kernel - Re: [PATCH] PCI: Allow pcie_aspm=force to work even when FADT indicates it is unsupported

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Message-ID: <CAAq6er0DUGcT_PuL3gOBNdcEVDxhW8EuP1dfFa_Sa9vNZmhfQA@mail.gmail.com>
Date:	Fri, 30 Mar 2012 10:55:36 +0100
From:	Andy Whitcroft <robobotbotbot@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Matthew Garrett <mjg@...hat.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, Colin King <colin.king@...onical.com>
Subject: Re: [PATCH] PCI: Allow pcie_aspm=force to work even when FADT
 indicates it is unsupported

On Thu, Mar 22, 2012 at 4:49 PM, Colin King <colin.king@...onical.com> wrote:
> From: Colin Ian King <colin.king@...onical.com>
>
> Right now using pcie_aspm=force will not enable ASPM if the FADT indicates
> ASPM is unsupported.  However, the semantics of force should probably allow
> for this, especially as they did before the ASPM disable rework with commit
> 3c076351c4027a56d5005a39a0b518a4ba393ce2
>
> This patch just skips the clearing of any ASPM setup that the firmware has
> carried out on this bus if pcie_aspm=force is being used.
>
> BugLink: https://bugs.launchpad.net/ubuntu/+bug/962038
>
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/pci/pcie/aspm.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index 24f049e..e406429 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -783,6 +783,9 @@ void pcie_clear_aspm(struct pci_bus *bus)
>  {
>        struct pci_dev *child;
>
> +       if (aspm_force)
> +               return;
> +
>        /*
>         * Clear any ASPM setup that the firmware has carried out on this bus
>         */
> --
> 1.7.9.1

Andrew, I believe the above is also needed to fix some additional
regressions with the new ASPM code.  If you are picking up the one
below this probably should go with it:

    + aspm-fix-pcie-devices-with-non-pcie-children.patch added to -mm tree

-apw
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