Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | [PATCH 9/10] PCI PM: Make pci_set_power_state() handle devices with no PM support | Date | Wed, 11 Mar 2009 10:55:50 +0100 |
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From: Rafael J. Wysocki <rjw@sisk.pl>
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: Rafael J. Wysocki <rjw@sisk.pl> --- drivers/pci/pci.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
Index: linux-2.6/drivers/pci/pci.c =================================================================== --- linux-2.6.orig/drivers/pci/pci.c +++ linux-2.6/drivers/pci/pci.c @@ -439,6 +439,10 @@ static int pci_raw_set_power_state(struc 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(struc * 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 * */ 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); }
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