nagai/kernel
3
0
Fork 0
forked from mirrors/linux
Code Pull requests Activity

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

Browse source 
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: c4b65157ae (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>
This commit is contained in:
Mika Westerberg 2018-04-20 15:22:02 +03:00 committed by Rafael J. Wysocki
parent 6d08b06e67
commit ae860a19f3
1 changed files with 3 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
drivers/pci/pci-driver.c
View file

@ -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;