From: Rafael J. Wysocki <rjw@xxxxxxx> After attempting to change the power state of a PCI device pci_raw_set_power_state() doesn't check if the value it wrote into the device's PCI_PM_CTRL register has been stored in there, but unconditionally modifies the device's current_state field to reflect the change. This may cause problems to happen if the power state of the device hasn't been changed in fact, because it will make the PCI PM core think that the device is in a power state it really is not in. To prevent such situations from happening modify pci_raw_set_power_state() so that it reads the device's PCI_PM_CTRL register after writing into it and uses the value read from the register to update the device's current_state field. Also make it print a message saying that the device refused to change its power state as requested (returning an error code in such cases would cause suspend regressions to appear on some systems, where device drivers' suspend routines return error codes if pci_set_power_state() fails). Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx> --- Respin to fix issues pointed out by the reviewers. Thanks, Rafael --- drivers/pci/pci.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) Index: linux-2.6/drivers/pci/pci.c =================================================================== --- linux-2.6.orig/drivers/pci/pci.c +++ linux-2.6/drivers/pci/pci.c @@ -513,7 +513,11 @@ static int pci_raw_set_power_state(struc else if (state == PCI_D2 || dev->current_state == PCI_D2) udelay(PCI_PM_D2_DELAY); - dev->current_state = state; + pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); + dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK); + if (dev->current_state != state && printk_ratelimit()) + dev_info(&dev->dev, "Refused to change power state, " + "currently in D%d\n", dev->current_state); /* According to section 5.4.1 of the "PCI BUS POWER MANAGEMENT * INTERFACE SPECIFICATION, REV. 1.2", a device transitioning _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
