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

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

[Mika Westerberg]

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@linux.intel.com>
---
 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

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

[Rafael J. Wysocki]

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@linux.intel.com>

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;
>  
> 

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

[Bjorn Helgaas]

On Mon, Apr 23, 2018 at 09:43:52AM +0200, Rafael J. Wysocki wrote:
> 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@linux.intel.com>
> 
> 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.

Thanks for taking it, that's perfect!

> > ---
> >  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;
> >  
> > 
> 
>