lkml.org 
[lkml]   [2020]   [Jan]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.19 395/639] PCI: PM: Avoid possible suspend-to-idle issue
    Date
    From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

    [ Upstream commit d491f2b75237ef37d8867830ab7fad8d9659e853 ]

    If a PCI driver leaves the device handled by it in D0 and calls
    pci_save_state() on the device in its ->suspend() or ->suspend_late()
    callback, it can expect the device to stay in D0 over the whole
    s2idle cycle. However, that may not be the case if there is a
    spurious wakeup while the system is suspended, because in that case
    pci_pm_suspend_noirq() will run again after pci_pm_resume_noirq()
    which calls pci_restore_state(), via pci_pm_default_resume_early(),
    so state_saved is cleared and the second iteration of
    pci_pm_suspend_noirq() will invoke pci_prepare_to_sleep() which
    may change the power state of the device.

    To avoid that, add a new internal flag, skip_bus_pm, that will be set
    by pci_pm_suspend_noirq() when it runs for the first time during the
    given system suspend-resume cycle if the state of the device has
    been saved already and the device is still in D0. Setting that flag
    will cause the next iterations of pci_pm_suspend_noirq() to set
    state_saved for pci_pm_resume_noirq(), so that it always restores the
    device state from the originally saved data, and avoid calling
    pci_prepare_to_sleep() for the device.

    Fixes: 33e4f80ee69b ("ACPI / PM: Ignore spurious SCI wakeups from suspend-to-idle")
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    Reviewed-by: Keith Busch <keith.busch@intel.com>
    Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/pci/pci-driver.c | 17 ++++++++++++++++-
    include/linux/pci.h | 1 +
    2 files changed, 17 insertions(+), 1 deletion(-)

    diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
    index bc1ff41ce3d35..5c9873fcbd08b 100644
    --- a/drivers/pci/pci-driver.c
    +++ b/drivers/pci/pci-driver.c
    @@ -736,6 +736,8 @@ static int pci_pm_suspend(struct device *dev)
    struct pci_dev *pci_dev = to_pci_dev(dev);
    const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

    + pci_dev->skip_bus_pm = false;
    +
    if (pci_has_legacy_pm_support(pci_dev))
    return pci_legacy_suspend(dev, PMSG_SUSPEND);

    @@ -829,7 +831,20 @@ static int pci_pm_suspend_noirq(struct device *dev)
    }
    }

    - if (!pci_dev->state_saved) {
    + if (pci_dev->skip_bus_pm) {
    + /*
    + * The function is running for the second time in a row without
    + * going through full resume, which is possible only during
    + * suspend-to-idle in a spurious wakeup case. Moreover, the
    + * device was originally left in D0, so its power state should
    + * not be changed here and the device register values saved
    + * originally should be restored on resume again.
    + */
    + pci_dev->state_saved = true;
    + } else if (pci_dev->state_saved) {
    + if (pci_dev->current_state == PCI_D0)
    + pci_dev->skip_bus_pm = true;
    + } else {
    pci_save_state(pci_dev);
    if (pci_power_manageable(pci_dev))
    pci_prepare_to_sleep(pci_dev);
    diff --git a/include/linux/pci.h b/include/linux/pci.h
    index b1f297f4b7b0b..94853094b6ef4 100644
    --- a/include/linux/pci.h
    +++ b/include/linux/pci.h
    @@ -342,6 +342,7 @@ struct pci_dev {
    D3cold, not set for devices
    powered on/off by the
    corresponding bridge */
    + unsigned int skip_bus_pm:1; /* Internal: Skip bus-level PM */
    unsigned int ignore_hotplug:1; /* Ignore hotplug events */
    unsigned int hotplug_user_indicators:1; /* SlotCtl indicators
    controlled exclusively by
    --
    2.20.1


    \
     
     \ /
      Last update: 2020-01-24 12:22    [W:4.070 / U:0.092 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site