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    SubjectRe: [PATCH 1/2] PCI PM: Follow PCI_PM_CTRL_NO_SOFT_RESET during transitions from D3
    On Mon, 18 May 2009 22:51:12 +0200
    "Rafael J. Wysocki" <rjw@sisk.pl> wrote:

    > From: Rafael J. Wysocki <rjw@sisk.pl>
    >
    > According to the PCI PM specification (PCI Bus Power Management
    > Interface Specification, Rev. 1.2, Section 5.4.1) we are supposed to
    > reinitialize devices that have PCI_PM_CTRL_NO_SOFT_RESET clear during
    > all transitions from PCI_D3hot to PCI_D0, but we only do it if the
    > device's current_state field is equal to PCI_UNKNOWN.
    >
    > This may lead to problems if a device with PCI_PM_CTRL_NO_SOFT_RESET
    > unset is put into PCI_D3hot at run time by its driver and
    > pci_set_power_state() is used to put it back into PCI_D0, because in
    > that case the device will remain uninitialized after
    > pci_set_power_state() has returned. Prevent that from happening by
    > modifying pci_raw_set_power_state() to reinitialize devices with
    > PCI_PM_CTRL_NO_SOFT_RESET unset during all transitions from D3 to D0.
    >
    > Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    > ---
    > drivers/pci/pci.c | 2 ++
    > 1 file changed, 2 insertions(+)
    >
    > Index: linux-2.6/drivers/pci/pci.c
    > ===================================================================
    > --- linux-2.6.orig/drivers/pci/pci.c
    > +++ linux-2.6/drivers/pci/pci.c
    > @@ -480,6 +480,8 @@ static int pci_raw_set_power_state(struc
    > pmcsr &= ~PCI_PM_CTRL_STATE_MASK;
    > pmcsr |= state;
    > break;
    > + case PCI_D3hot:
    > + case PCI_D3cold:
    > case PCI_UNKNOWN: /* Boot-up */
    > if ((pmcsr & PCI_PM_CTRL_STATE_MASK) == PCI_D3hot
    > && !(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))
    >

    Applied to my linux-next branch, thanks Rafael. I've also included
    stable@kernel.org in the cc, since this is a small but important fix.

    --
    Jesse Barnes, Intel Open Source Technology Center


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