On Friday, April 20, 2018 2:22:02 PM CEST Mika Westerberg wrote:
> 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>
Since this fixes a commit that went in through the PM tree, I've queued it up.
Bjorn, please let me know if you prefer to route it through the PCI tree.
> ---
> 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;
>
>
