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Commit 4a865905 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
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PCI PM: Make pci_set_power_state() handle devices with no PM support 



There is a problem with PCI devices without any PM support (either
native or through the platform) that pci_set_power_state() always
returns error code for them, even if they are being put into D0.
However, such devices are always in D0, so pci_set_power_state()
should return success when attempting to put such a device into D0.
It also should update the current_state field for these devices as
appropriate.  This modification is necessary so that the standard
configuration registers of these devices are successfully restored by
pci_restore_standard_config() during the "early" phase of resume.

In addition, pci_set_power_state() should check the value of
current_state before calling the platform to change the power state
of the device to avoid doing that unnecessarily.

Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Acked-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent 46939f8b

drivers/pci/pci.c

+12 −6
Original line number Diff line number Diff line
@@ -439,6 +439,10 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state) 
	u16 pmcsr;

	bool need_restore = false;



	/* Check if we're already there */

	if (dev->current_state == state)

		return 0;



	if (!dev->pm_cap)

		return -EIO;
@@ -449,10 +453,7 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state) 
	 * Can enter D0 from any state, but if we can only go deeper 

	 * to sleep if we're already in a low power state

	 */

	if (dev->current_state == state) {

		/* we're already there */

		return 0;

	} else if (state != PCI_D0 && dev->current_state <= PCI_D3cold

	if (state != PCI_D0 && dev->current_state <= PCI_D3cold

	    && dev->current_state > state) {

		dev_err(&dev->dev, "invalid power transition "

			"(from state %d to %d)\n", dev->current_state, state);
@@ -570,12 +571,17 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state) 
		 */

		return 0;



	if (state == PCI_D0 && platform_pci_power_manageable(dev)) {

	/* Check if we're already there */

	if (dev->current_state == state)

		return 0;



	if (state == PCI_D0) {

		/*

		 * Allow the platform to change the state, for example via ACPI

		 * _PR0, _PS0 and some such, but do not trust it.

		 */

		int ret = platform_pci_set_power_state(dev, PCI_D0);

		int ret = platform_pci_power_manageable(dev) ?

			platform_pci_set_power_state(dev, PCI_D0) : 0;

		if (!ret)

			pci_update_current_state(dev, PCI_D0);

	}