PCI/PM: Rearrange pci_set_power_state()

The part of pci_set_power_state() related to transitions into
low-power states is unnecessary convoluted, so clearly divide it
into the D3cold special case and the general case covering all of
the other states.

Also fix a potential issue with calling pci_bus_set_current_state()
to set the current state of all devices on the subordinate bus to
D3cold without checking if the power state of the parent bridge has
really changed to D3cold.

Link: https://lore.kernel.org/r/2139440.Mh6RI2rZIc@kreacher
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b6ad2fa..df88609 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1446,19 +1446,25 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
        if (state >= PCI_D3hot && (dev->dev_flags & PCI_DEV_FLAGS_NO_D3))
                return 0;
 
-       /*
-        * To put device in D3cold, we put device into D3hot in native
-        * way, then put device into D3cold with platform ops
-        */
-       error = pci_set_low_power_state(dev, state > PCI_D3hot ?
-                                       PCI_D3hot : state);
+       if (state == PCI_D3cold) {
+               /*
+                * To put the device in D3cold, put it into D3hot in the native
+                * way, then put it into D3cold using platform ops.
+                */
+               error = pci_set_low_power_state(dev, PCI_D3hot);
 
-       if (pci_platform_power_transition(dev, state))
-               return error;
+               if (pci_platform_power_transition(dev, PCI_D3cold))
+                       return error;
 
-       /* Powering off a bridge may power off the whole hierarchy */
-       if (state == PCI_D3cold)
-               pci_bus_set_current_state(dev->subordinate, PCI_D3cold);
+               /* Powering off a bridge may power off the whole hierarchy */
+               if (dev->current_state == PCI_D3cold)
+                       pci_bus_set_current_state(dev->subordinate, PCI_D3cold);
+       } else {
+               error = pci_set_low_power_state(dev, state);
+
+               if (pci_platform_power_transition(dev, state))
+                       return error;
+       }
 
        return 0;
 }