Revert "PCI: PM: Do not read power state in pci_enable_device_flags()"

Revert commit 4514d99 ("PCI: PM: Do not read power state in pci_enable_device_flags()") that is reported to cause PCI device initialization issues on some systems. BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=213481 Link: https://lore.kernel.org/linux-acpi/[email protected] Reported-by: Michael <[email protected]> Reported-by: Salvatore Bonaccorso <[email protected]> Fixes: 4514d99 ("PCI: PM: Do not read power state in pci_enable_device_flags()") Signed-off-by: Rafael J. Wysocki <[email protected]>
wafgo · Jun 22, 2021 · 4d6035f · 4d6035f
1 parent 13311e7
commit 4d6035f
Showing 1 changed file with 13 additions and 3 deletions.
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
@@ -1900,11 +1900,21 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags)
 	int err;
 	int i, bars = 0;
 
-	if (atomic_inc_return(&dev->enable_cnt) > 1) {
-		pci_update_current_state(dev, dev->current_state);
-		return 0;		/* already enabled */
+	/*
+	 * Power state could be unknown at this point, either due to a fresh
+	 * boot or a device removal call.  So get the current power state
+	 * so that things like MSI message writing will behave as expected
+	 * (e.g. if the device really is in D0 at enable time).
+	 */
+	if (dev->pm_cap) {
+		u16 pmcsr;
+		pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
+		dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK);
 	}
 
+	if (atomic_inc_return(&dev->enable_cnt) > 1)
+		return 0;		/* already enabled */
+
 	bridge = pci_upstream_bridge(dev);
 	if (bridge)
 		pci_enable_bridge(bridge);