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    Subject[PATCH resend] ASPM: Fix pcie devices with non-pcie children
    From: Matthew Garrett <mjg@redhat.com>
    Date: Tue, 27 Mar 2012 10:17:41 -0400

    Since 3.2.12 and 3.3, some systems are failing to boot with a BUG_ON.
    Some other systems using the pata_jmicron driver fail to boot because
    no disks are detected. Passing pcie_aspm=force on the kernel command
    line works around it.

    The cause: commit 4949be16822e ("PCI: ignore pre-1.1 ASPM quirking
    when ASPM is disabled") changed the behaviour of
    pcie_aspm_sanity_check() to always return 0 if aspm is disabled, in
    order to avoid cases where we changed ASPM state on pre-PCIe 1.1
    devices. This skipped the secondary function of
    pcie_aspm_sanity_check which was to avoid us enabling ASPM on devices
    that had non-PCIe children, causing trouble later on. Move the
    aspm_disabled check so we continue to honour that scenario.

    Addresses https://bugzilla.kernel.org/show_bug.cgi?id=42979 and
    http://bugs.debian.org/665420

    [jn: with more symptoms in log message]

    Reported-by: Romain Francoise <romain@orebokech.com> # kernel panic
    Reported-by: Chris Holland <bandidoirlandes@gmail.com> # disk detection trouble
    Signed-off-by: Matthew Garrett <mjg@redhat.com>
    Cc: stable@vger.kernel.org
    Tested-by: Hatem Masmoudi <hatem.masmoudi@gmail.com> # Dell Latitude E5520
    Tested-by: janek <jan0x6c@gmail.com> # pata_jmicron with JMB362/JMB363
    Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
    ---
    Hi Andrew,

    This patch only appeared a couple of days ago[1], but it fixes a
    noticeable regression so I would like to make sure the patch becomes
    part of mainline and the 3.2.y- and 3.3.y-stable trees soon. Could
    you pick it up for linux-next until it makes its way to the PCI tree?

    Regression was introduced between 3.3-rc7 and 3.3 and between 3.2.11
    and 3.2.12. Prevents boot on affected machines, though there is a
    workaround. Details about the symptoms and fix are above.

    Thanks,
    Jonathan

    [1] http://thread.gmane.org/gmane.linux.kernel.pci/14503

    drivers/pci/pcie/aspm.c | 13 ++++++++++---
    1 file changed, 10 insertions(+), 3 deletions(-)

    diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
    index 4bdef24cd412..b500840a143b 100644
    --- a/drivers/pci/pcie/aspm.c
    +++ b/drivers/pci/pcie/aspm.c
    @@ -508,9 +508,6 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
    int pos;
    u32 reg32;

    - if (aspm_disabled)
    - return 0;
    -
    /*
    * Some functions in a slot might not all be PCIe functions,
    * very strange. Disable ASPM for the whole slot
    @@ -519,6 +516,16 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
    pos = pci_pcie_cap(child);
    if (!pos)
    return -EINVAL;
    +
    + /*
    + * If ASPM is disabled then we're not going to change
    + * the BIOS state. It's safe to continue even if it's a
    + * pre-1.1 device
    + */
    +
    + if (aspm_disabled)
    + continue;
    +
    /*
    * Disable ASPM for pre-1.1 PCIe device, we follow MS to use
    * RBER bit to determine if a function is 1.1 version device
    --
    1.7.10.rc1


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