From: Bjorn Helgaas <[email protected]> pci_raw_set_power_state() uses the Power Management capability to change a device's power state. The capability is in config space, which is accessible in D0, D1, D2, and D3hot, but not in D3cold.
If we call pci_raw_set_power_state() on a device that's in D3cold, config reads fail and return ~0 data, which we erroneously interpreted as "the device is in D3hot", leading to messages like this: pcieport 0000:03:00.0: Refused to change power state, currently in D3 The PCI_PM_CTRL has several RsvdP fields, so ~0 is never a valid register value. Notice if we get that data, print a more informative message, and return an error. Changing the power state of a device from D3cold must be done by a platform power management method or some other non-config space mechanism. Signed-off-by: Bjorn Helgaas <[email protected]> --- drivers/pci/pci.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 5f0a3145c3f2..41112af189a8 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -853,6 +853,12 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state) return -EIO; pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); + if (pmcsr == (u16) PCI_ERROR_RESPONSE) { + pci_err(dev, "can't access config space to change power state from %s to %s\n", + pci_power_name(dev->current_state), + pci_power_name(state)); + return -EIO; + } /* * If we're (effectively) in D3, force entire word to 0. @@ -893,8 +899,9 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t 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()) - pci_info(dev, "refused to change power state (currently %s)\n", - pci_power_name(dev->current_state)); + pci_info(dev, "refused to change power state from %s to %s\n", + pci_power_name(dev->current_state), + pci_power_name(state)); /* * According to section 5.4.1 of the "PCI BUS POWER MANAGEMENT -- 2.23.0.187.g17f5b7556c-goog
