PCI / PM: Do not clear state_saved in pci_pm_freeze() when smart suspend is set

If a driver uses DPM_FLAG_SMART_SUSPEND and the device is already
runtime suspended when hibernate is started PCI core skips runtime
resuming the device but still clears pci_dev->state_saved. After the
hibernation image is written pci_pm_thaw_noirq() makes sure subsequent
thaw phases for the device are also skipped leaving it runtime suspended
with pci_dev->state_saved == false.

When the device is eventually runtime resumed pci_pm_runtime_resume()
restores config space by calling pci_restore_standard_config(), however
because pci_dev->state_saved == false pci_restore_state() never actually
restores the config space leaving the device in a state that is not what
the driver might expect.

For example here is what happens for intel-lpss I2C devices once the
hibernation snapshot is taken:

  intel-lpss 0000:00:15.0: power state changed by ACPI to D0
  intel-lpss 0000:00:1e.0: power state changed by ACPI to D3cold
  video LNXVIDEO:00: Restoring backlight state
  PM: hibernation exit
  i2c_designware i2c_designware.1: Unknown Synopsys component type: 0xffffffff
  i2c_designware i2c_designware.0: Unknown Synopsys component type: 0xffffffff
  i2c_designware i2c_designware.1: timeout in disabling adapter
  i2c_designware i2c_designware.0: timeout in disabling adapter

Since PCI config space is not restored the device is still in D3hot
making MMIO register reads return 0xffffffff.

Fix this by clearing pci_dev->state_saved only if we actually end up
runtime resuming the device.

Fixes: c4b65157aeef (PCI / PM: Take SMART_SUSPEND driver flag into account)
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: 4.15+ <stable@vger.kernel.org> # 4.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 6ace47099fc59451422daaf7d38c52f470c9c500..b9a131137e64b86be6660d9d94225e5ff0b8aeb9 100644 (file)
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -958,10 +958,11 @@ static int pci_pm_freeze(struct device *dev)
         * devices should not be touched during freeze/thaw transitions,
         * however.
         */
-       if (!dev_pm_test_driver_flags(dev, DPM_FLAG_SMART_SUSPEND))
+       if (!dev_pm_smart_suspend_and_suspended(dev)) {
                pm_runtime_resume(dev);
+               pci_dev->state_saved = false;
+       }
 
-       pci_dev->state_saved = false;
        if (pm->freeze) {
                int error;