Commit 471a739a authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PCI: PM: Avoid skipping bus-level PM on platforms without ACPI 



There are platforms that do not call pm_set_suspend_via_firmware(),
so pm_suspend_via_firmware() returns 'false' on them, but the power
states of PCI devices (PCIe ports in particular) are changed as a
result of powering down core platform components during system-wide
suspend.  Thus the pm_suspend_via_firmware() checks in
pci_pm_suspend_noirq() and pci_pm_resume_noirq() introduced by
commit 3e26c5fe ("PCI: PM: Skip devices in D0 for suspend-to-
idle") are not sufficient to determine that devices left in D0
during suspend will remain in D0 during resume and so the bus-level
power management can be skipped for them.

For this reason, introduce a new global suspend flag,
PM_SUSPEND_FLAG_NO_PLATFORM, set it for suspend-to-idle only
and replace the pm_suspend_via_firmware() checks mentioned above
with checks against this flag.

Fixes: 3e26c5fe ("PCI: PM: Skip devices in D0 for suspend-to-idle")
Reported-by: default avatarJon Hunter <jonathanh@nvidia.com>
Tested-by: default avatarJon Hunter <jonathanh@nvidia.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
parent 4b972a01

drivers/pci/pci-driver.c

+4 −4
Original line number Diff line number Diff line
@@ -859,7 +859,7 @@ static int pci_pm_suspend_noirq(struct device *dev) 
			pci_dev->bus->self->skip_bus_pm = true;

	}



	if (pci_dev->skip_bus_pm && !pm_suspend_via_firmware()) {

	if (pci_dev->skip_bus_pm && pm_suspend_no_platform()) {

		dev_dbg(dev, "PCI PM: Skipped\n");

		goto Fixup;

	}
@@ -914,10 +914,10 @@ static int pci_pm_resume_noirq(struct device *dev) 
	/*

	 * In the suspend-to-idle case, devices left in D0 during suspend will

	 * stay in D0, so it is not necessary to restore or update their

	 * configuration here and attempting to put them into D0 again may

	 * confuse some firmware, so avoid doing that.

	 * configuration here and attempting to put them into D0 again is

	 * pointless, so avoid doing that.

	 */

	if (!pci_dev->skip_bus_pm || pm_suspend_via_firmware())

	if (!(pci_dev->skip_bus_pm && pm_suspend_no_platform()))

		pci_pm_default_resume_early(pci_dev);



	pci_fixup_device(pci_fixup_resume_early, pci_dev);

include/linux/suspend.h

+24 −2
Original line number Diff line number Diff line
@@ -209,8 +209,9 @@ extern int suspend_valid_only_mem(suspend_state_t state); 


extern unsigned int pm_suspend_global_flags;



#define PM_SUSPEND_FLAG_FW_SUSPEND	(1 << 0)

#define PM_SUSPEND_FLAG_FW_RESUME	(1 << 1)

#define PM_SUSPEND_FLAG_FW_SUSPEND	BIT(0)

#define PM_SUSPEND_FLAG_FW_RESUME	BIT(1)

#define PM_SUSPEND_FLAG_NO_PLATFORM	BIT(2)



static inline void pm_suspend_clear_flags(void)

{
@@ -227,6 +228,11 @@ static inline void pm_set_resume_via_firmware(void) 
	pm_suspend_global_flags |= PM_SUSPEND_FLAG_FW_RESUME;

}



static inline void pm_set_suspend_no_platform(void)

{

	pm_suspend_global_flags |= PM_SUSPEND_FLAG_NO_PLATFORM;

}



/**

 * pm_suspend_via_firmware - Check if platform firmware will suspend the system.

 *
@@ -268,6 +274,22 @@ static inline bool pm_resume_via_firmware(void) 
	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_FW_RESUME);

}



/**

 * pm_suspend_no_platform - Check if platform may change device power states.

 *

 * To be called during system-wide power management transitions to sleep states

 * or during the subsequent system-wide transitions back to the working state.

 *

 * Return 'true' if the power states of devices remain under full control of the

 * kernel throughout the system-wide suspend and resume cycle in progress (that

 * is, if a device is put into a certain power state during suspend, it can be

 * expected to remain in that state during resume).

 */

static inline bool pm_suspend_no_platform(void)

{

	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_NO_PLATFORM);

}



/* Suspend-to-idle state machnine. */

enum s2idle_states {

	S2IDLE_STATE_NONE,      /* Not suspended/suspending. */

kernel/power/suspend.c

+3 −0
Original line number Diff line number Diff line
@@ -493,6 +493,9 @@ int suspend_devices_and_enter(suspend_state_t state) 


	pm_suspend_target_state = state;



	if (state == PM_SUSPEND_TO_IDLE)

		pm_set_suspend_no_platform();



	error = platform_suspend_begin(state);

	if (error)

		goto Close;

CRA Git | Maintained and supported by SUSTech CRA and CCSE