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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/[email protected] Signed-off-by: Bjorn Helgaas <[email protected]> Reviewed-by: Rafael J. Wysocki <[email protected]> Reviewed-by: Keith Busch <[email protected]> Reviewed-by: Mika Westerberg <[email protected]>
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