[PATCH v1 10/11] PCI/PM: Rearrange pci_set_power_state()

Rafael J. Wysocki
2022-05-05T18:31:54Z

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.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
drivers/pci/pci.c | 28 +++++++++++++++++-----------
1 file changed, 17 insertions(+), 11 deletions(-)

Index: linux-pm/drivers/pci/pci.c
===================================================================
--- linux-pm.orig/drivers/pci/pci.c
+++ linux-pm/drivers/pci/pci.c
@@ -1446,19 +1446,25 @@ int pci_set_power_state(struct pci_dev *
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;
}