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    Subject[PATCH 3/6 v2] PCI / PM: Detect early wakeup in pci_pm_prepare()
    Date
    From: Rafael J. Wysocki <rjw@sisk.pl>

    A subsequent patch is going to move the invocation of
    pm_runtime_barrier() from dpm_prepare() to __device_suspend().
    Consequently, early wakeup events resulting from runtime resume
    requests for wakeup devices queued up right before system suspend
    will only be detected after all of the subsystem-level .prepare()
    callbacks have run. However, the PCI bus type calls
    pm_runtime_get_sync() from its pci_pm_prepare() callback routine,
    so it would destroy the early wakeup events information regarding PCI
    devices. To prevent this from happening add an early wakeup
    detection mechanism, analogous to the one currently in dpm_prepare(),
    to pci_pm_prepare().

    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    ---
    drivers/pci/pci-driver.c | 16 +++++++++++++++-
    1 file changed, 15 insertions(+), 1 deletion(-)

    Index: linux-2.6/drivers/pci/pci-driver.c
    ===================================================================
    --- linux-2.6.orig/drivers/pci/pci-driver.c
    +++ linux-2.6/drivers/pci/pci-driver.c
    @@ -18,6 +18,7 @@
    #include <linux/sched.h>
    #include <linux/cpu.h>
    #include <linux/pm_runtime.h>
    +#include <linux/suspend.h>
    #include "pci.h"

    struct pci_dynid {
    @@ -616,6 +617,19 @@ static int pci_pm_prepare(struct device
    int error = 0;

    /*
    + * If a PCI device configured to wake up the system from sleep states
    + * has been suspended at run time and there's a resume request pending
    + * for it, this is equivalent to the device signaling wakeup, so the
    + * system suspend operation should be aborted.
    + */
    + pm_runtime_get_noresume(dev);
    + if (pm_runtime_barrier(dev) && device_may_wakeup(dev))
    + pm_wakeup_event(dev, 0);
    +
    + if (pm_wakeup_pending())
    + return -EBUSY;
    +
    + /*
    * PCI devices suspended at run time need to be resumed at this
    * point, because in general it is necessary to reconfigure them for
    * system suspend. Namely, if the device is supposed to wake up the
    @@ -624,7 +638,7 @@ static int pci_pm_prepare(struct device
    * system from the sleep state, we'll have to prevent it from signaling
    * wake-up.
    */
    - pm_runtime_get_sync(dev);
    + pm_runtime_resume(dev);

    if (drv && drv->pm && drv->pm->prepare)
    error = drv->pm->prepare(dev);


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