PCI: Autosense device removal in pci_bridge_d3_update()

The algorithm to update the flag indicating whether a bridge may go to D3
makes a few optimizations based on whether the update was caused by the
removal of a device on the one hand, versus the addition of a device or the
change of its D3cold flags on the other hand.

The information whether the update pertains to a removal is currently
passed in by the caller, but the function may as well determine that itself
by examining the device in question, thereby allowing for a considerable
simplification and reduction of the code.

Out of several options to determine removal, I've chosen the function
device_is_registered() because it's cheap:  It merely returns the
dev->kobj.state_in_sysfs flag.  That flag is set through device_add() when
the root bus is scanned and cleared through device_remove().  The call to
pci_bridge_d3_update() happens after each of these calls, respectively, so
the ordering is correct.

No functional change intended.
Tested-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/pci/bus.c

@@ -320,7 +320,7 @@ void pci_bus_add_device(struct pci_dev *dev)
 	pci_fixup_device(pci_fixup_final, dev);
 	pci_create_sysfs_dev_files(dev);
 	pci_proc_attach_device(dev);
-	pci_bridge_d3_device_changed(dev);
+	pci_bridge_d3_update(dev);
 
 	dev->match_driver = true;
 	retval = device_attach(&dev->dev);

drivers/pci/pci.c

@@ -2281,14 +2281,14 @@ static int pci_dev_check_d3cold(struct pci_dev *dev, void *data)
 /*
  * pci_bridge_d3_update - Update bridge D3 capabilities
  * @dev: PCI device which is changed
- * @remove: Is the device being removed
  *
  * Update upstream bridge PM capabilities accordingly depending on if the
  * device PM configuration was changed or the device is being removed.  The
  * change is also propagated upstream.
  */
-static void pci_bridge_d3_update(struct pci_dev *dev, bool remove)
+void pci_bridge_d3_update(struct pci_dev *dev)
 {
+	bool remove = !device_is_registered(&dev->dev);
 	struct pci_dev *bridge;
 	bool d3cold_ok = true;
 
@@ -2315,35 +2315,10 @@ static void pci_bridge_d3_update(struct pci_dev *dev, bool remove)
 	if (bridge->bridge_d3 != d3cold_ok) {
 		bridge->bridge_d3 = d3cold_ok;
 		/* Propagate change to upstream bridges */
-		pci_bridge_d3_update(bridge, false);
+		pci_bridge_d3_update(bridge);
 	}
 }
 
-/**
- * pci_bridge_d3_device_changed - Update bridge D3 capabilities on change
- * @dev: PCI device that was changed
- *
- * If a device is added or its PM configuration, such as is it allowed to
- * enter D3cold, is changed this function updates upstream bridge PM
- * capabilities accordingly.
- */
-void pci_bridge_d3_device_changed(struct pci_dev *dev)
-{
-	pci_bridge_d3_update(dev, false);
-}
-
-/**
- * pci_bridge_d3_device_removed - Update bridge D3 capabilities on remove
- * @dev: PCI device being removed
- *
- * Function updates upstream bridge PM capabilities based on other devices
- * still left on the bus.
- */
-void pci_bridge_d3_device_removed(struct pci_dev *dev)
-{
-	pci_bridge_d3_update(dev, true);
-}
-
 /**
  * pci_d3cold_enable - Enable D3cold for device
  * @dev: PCI device to handle
@@ -2356,7 +2331,7 @@ void pci_d3cold_enable(struct pci_dev *dev)
 {
 	if (dev->no_d3cold) {
 		dev->no_d3cold = false;
-		pci_bridge_d3_device_changed(dev);
+		pci_bridge_d3_update(dev);
 	}
 }
 EXPORT_SYMBOL_GPL(pci_d3cold_enable);
@@ -2373,7 +2348,7 @@ void pci_d3cold_disable(struct pci_dev *dev)
 {
 	if (!dev->no_d3cold) {
 		dev->no_d3cold = true;
-		pci_bridge_d3_device_changed(dev);
+		pci_bridge_d3_update(dev);
 	}
 }
 EXPORT_SYMBOL_GPL(pci_d3cold_disable);

drivers/pci/pci.h

@@ -85,8 +85,7 @@ void pci_pm_init(struct pci_dev *dev);
 void pci_ea_init(struct pci_dev *dev);
 void pci_allocate_cap_save_buffers(struct pci_dev *dev);
 void pci_free_cap_save_buffers(struct pci_dev *dev);
-void pci_bridge_d3_device_changed(struct pci_dev *dev);
-void pci_bridge_d3_device_removed(struct pci_dev *dev);
+void pci_bridge_d3_update(struct pci_dev *dev);
 
 static inline void pci_wakeup_event(struct pci_dev *dev)
 {

drivers/pci/remove.c

@@ -40,7 +40,7 @@ static void pci_destroy_dev(struct pci_dev *dev)
 	list_del(&dev->bus_list);
 	up_write(&pci_bus_sem);
 
-	pci_bridge_d3_device_removed(dev);
+	pci_bridge_d3_update(dev);
 	pci_free_resources(dev);
 	put_device(&dev->dev);
 }