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Commit c5eb1190 authored by Jarkko Nikula's avatar Jarkko Nikula Committed by Bjorn Helgaas
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PCI / PM: Allow runtime PM without callback functions 



a9c8088c ("i2c: i801: Don't restore config registers on runtime PM")
nullified the runtime PM suspend/resume callback pointers while keeping the
runtime PM enabled.

This caused the SMBus PCI device to stay in D0 with
/sys/devices/.../power/runtime_status showing "error" when the runtime PM
framework attempted to autosuspend the device.  This is due to PCI bus
runtime PM, which checks for driver runtime PM callbacks and returns
-ENOSYS if they are not set.

Since i2c-i801.c doesn't need to do anything device-specific for runtime
PM, Jean Delvare proposed this be fixed in the PCI core rather than adding
dummy runtime PM callback functions in the PCI drivers.

Change pci_pm_runtime_suspend()/pci_pm_runtime_resume() so they allow
changing the PCI device power state during runtime PM transitions even if
the driver supplies no runtime PM callbacks.

This fixes the runtime PM regression on i2c-i801.c.

It is not obvious why the code previously required the runtime PM
callbacks.  The test has been there since the code was introduced by
6cbf8214 ("PCI PM: Run-time callbacks for PCI bus type").

On the other hand, a similar change was done to generic runtime PM
callbacks in 05aa55dd ("PM / Runtime: Lenient generic runtime pm
callbacks").

Fixes: a9c8088c ("i2c: i801: Don't restore config registers on runtime PM")
Reported-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: default avatarJarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarJean Delvare <jdelvare@suse.de>
Reviewed-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: stable@vger.kernel.org	# v4.18+
parent 65102238

drivers/pci/pci-driver.c

+12 −15
Original line number Original line Diff line number Diff line
@@ -1251,30 +1251,29 @@ static int pci_pm_runtime_suspend(struct device *dev) 
		return 0;

		return 0;

	}

	}





	if (!pm || !pm->runtime_suspend)

		return -ENOSYS;



	pci_dev->state_saved = false;

	pci_dev->state_saved = false;

	if (pm && pm->runtime_suspend) {

		error = pm->runtime_suspend(dev);

		error = pm->runtime_suspend(dev);

	if (error) {

		/*

		/*

		 * -EBUSY and -EAGAIN is used to request the runtime PM core

		 * -EBUSY and -EAGAIN is used to request the runtime PM core

		 * to schedule a new suspend, so log the event only with debug

		 * to schedule a new suspend, so log the event only with debug

		 * log level.

		 * log level.

		 */

		 */

		if (error == -EBUSY || error == -EAGAIN)

		if (error == -EBUSY || error == -EAGAIN) {

			dev_dbg(dev, "can't suspend now (%pf returned %d)\n",

			dev_dbg(dev, "can't suspend now (%pf returned %d)\n",

				pm->runtime_suspend, error);

				pm->runtime_suspend, error);

		else

			return error;

		} else if (error) {

			dev_err(dev, "can't suspend (%pf returned %d)\n",

			dev_err(dev, "can't suspend (%pf returned %d)\n",

				pm->runtime_suspend, error);

				pm->runtime_suspend, error);



			return error;

			return error;

		}

		}

	}





	pci_fixup_device(pci_fixup_suspend, pci_dev);

	pci_fixup_device(pci_fixup_suspend, pci_dev);





	if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0

	if (pm && pm->runtime_suspend

	    && !pci_dev->state_saved && pci_dev->current_state != PCI_D0

	    && pci_dev->current_state != PCI_UNKNOWN) {

	    && pci_dev->current_state != PCI_UNKNOWN) {

		WARN_ONCE(pci_dev->current_state != prev,

		WARN_ONCE(pci_dev->current_state != prev,

			"PCI PM: State of device not saved by %pF\n",

			"PCI PM: State of device not saved by %pF\n",
@@ -1292,7 +1291,7 @@ static int pci_pm_runtime_suspend(struct device *dev) 




static int pci_pm_runtime_resume(struct device *dev)

static int pci_pm_runtime_resume(struct device *dev)

{

{

	int rc;

	int rc = 0;

	struct pci_dev *pci_dev = to_pci_dev(dev);

	struct pci_dev *pci_dev = to_pci_dev(dev);

	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;

	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
@@ -1306,13 +1305,11 @@ static int pci_pm_runtime_resume(struct device *dev) 
	if (!pci_dev->driver)

	if (!pci_dev->driver)

		return 0;

		return 0;





	if (!pm || !pm->runtime_resume)

		return -ENOSYS;



	pci_fixup_device(pci_fixup_resume_early, pci_dev);

	pci_fixup_device(pci_fixup_resume_early, pci_dev);

	pci_enable_wake(pci_dev, PCI_D0, false);

	pci_enable_wake(pci_dev, PCI_D0, false);

	pci_fixup_device(pci_fixup_resume, pci_dev);

	pci_fixup_device(pci_fixup_resume, pci_dev);





	if (pm && pm->runtime_resume)

		rc = pm->runtime_resume(dev);

		rc = pm->runtime_resume(dev);





	pci_dev->runtime_d3cold = false;

	pci_dev->runtime_d3cold = false;