From 327ccbbcc1497bff6d6f543c1f37c43a1653671f Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 1 Aug 2019 11:50:56 -0500 Subject: PCI/PM: Return error when changing power state from D3cold 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. If we get that value, 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. Link: https://lore.kernel.org/r/20190822200551.129039-4-helgaas@kernel.org Signed-off-by: Bjorn Helgaas Reviewed-by: Rafael J. Wysocki Reviewed-by: Keith Busch Reviewed-by: Mika Westerberg --- drivers/pci/pci.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'drivers/pci/pci.c') diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 3376c663035d..d6ff1a98bd8d 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) ~0) { + pci_err(dev, "can't change power state from %s to %s (config space inaccessible)\n", + pci_power_name(dev->current_state), + pci_power_name(state)); + return -EIO; + } /* * If we're (effectively) in D3, force entire word to 0. -- cgit v1.2.3-59-g8ed1b