linux-kernel - [PATCH 4.16 089/113] PCI / PM: Do not clear state_saved in pci_pm

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Message-Id: <20180430184018.963429646@linuxfoundation.org>
Date:   Mon, 30 Apr 2018 12:25:00 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.16 089/113] PCI / PM: Do not clear state_saved in pci_pm_freeze() when smart suspend is set

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mika Westerberg <mika.westerberg@...ux.intel.com>

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 <mika.westerberg@...ux.intel.com>
Cc: 4.15+ <stable@...r.kernel.org> # 4.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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;