4.16-stable review patch. If anyone has any objections, please let me know.
------------------ From: Mika Westerberg <[email protected]> commit ae860a19f37c686e7c5816e96640168b7174a096 upstream. 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 <[email protected]> Cc: 4.15+ <[email protected]> # 4.15+ Signed-off-by: Rafael J. Wysocki <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/pci/pci-driver.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -945,10 +945,11 @@ static int pci_pm_freeze(struct device * * 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;
