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@xxxxxxxxxxxxxxx>
---
drivers/pci/pci-driver.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 6ace47099fc5..b9a131137e64 100644
--- 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;
--
2.17.0
