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

westeri · rafaeljw · commit ae860a19f37c · 2018-04-23T08:57:35.000+02:00
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: c4b6515 (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
@@ -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;
 
